View Full Version : Heat is bad. DI rifles get hot. DI rifles are bad.
...the title is meant to be in jest, by the way. http://vuurwapenblog.com/2010/04/04/heat-dissipation-two-schools-of-thought/
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Heat is discussed fairly often on various internet forums, especially when two subjects come up: barrel profile and method of operation.
We often see comments about how light barrels heat up too quickly. This is partially true – a lighter barrel will generally heat up faster than a heavy barrel. The “too” part is where the problem lies. Too fast for a machine gun barrel? Most likely. When you’re putting out a sustained rate of fire that can reach several hundred rounds per minute, a light barrel is definitely unsatisfactory. However, if you have a rifle, and not a machine gun, a lighter profile barrel may not heat up “too quickly”.
Also, there are many comments about how cool piston/op-rod systems run. I’ve never found touching the bolt carrier after firing to be a necessary exercise, but some find it to be very important, or at least fun. However, it’s not as if the presence of the op-rod has a chilling effect on the barrel, which is a critical component of the rifle, to be sure.
So we have two schools of thought here: that a lightweight barrel profile is more appropriate for use on a carbine, and that the standard system of operation is not unnecessarily hot; and that a heavy (or fluted/heavy) barrel is more appropriate for use on a carbine (or maybe a carbine machine gun to be used for laying down suppressive fire), and that an op-rod allows the rifle to run cooler.
Recently, while doing some experiments with standard plastic handguards, I thought I’d also compare a civilian legal M4 clone, or close to it – a Spike’s Tactical M4 LE with a Knight’s Armament M4 RAS handguard – with two Patriot Ordnance Factory rifles. One is a P-415, which uses POF’s op-rod system, and the other is called the RDIK, and it uses a gas tube, just like a standard AR-15. However, it’s equipped with the same heavy fluted barrel, heat sink gas block, reinforced upper receiver, and single piece railed forend that the P-415 uses.
To complete this test, I fired 30 rounds of 5.56mm ammunition through each rifle, then measured the temperature of the handguards in four separate places, as well as the temperature of the gas block/barrel. I measured these temperatures immediately after firing, 1 minute after firing, 5 minutes after firing, and 10 minutes after firing, using an infrared thermometer. I also measured the temperature of the bolt face immediately after firing.
Here are the handguard temperatures:
http://www.545ar.com/heataveragevs.jpg
Note that all three handguards got progressively hotter until sometime after the 5 minute mark. I found it interesting that the POF gas tube upper was within several degrees – up or down – of the P-415 op-rod upper during the whole exercise. I also found it interesting that every handguard had reached essentially the same temperature 10 minutes after firing.
Here are the gas block/barrel temperatures.
http://www.545ar.com/heatGBvs.jpg
I was shocked – honestly – to see how cool the POF RDIK gas block was after firing. There was a greater initial temperature difference between it and the P-415 gas block than there was between the P-415 and the Spike’s M4 LE. In addition, the M4 cooled faster than the P-415, as you can see, though each upper had roughly the same temperature loss profile after 1 minute.
This proves an often-overlooked point: while light barrels do heat up faster than heavy barrels, they also cool down faster than heavy barrels – apparently, faster than even a heavy fluted barrel. This also proves true a comment made to me by an industry professional while we were discussing this topic: that the gas block of a piston/op-rod rifle gets very, very hot.
As a side note, the temperature of the M4’s bolt immediately after firing was 94 degrees; the P-415’s bolt temperature was 88 degrees. The RDIK’s bolt was 89 degrees.
Although this was a very limited and rather unscientific test, it would seem that the vast majority of the POF rifles’ cooling ability comes from the heat sink barrel nut, handguard, fluting, etc, and not from the piston/op-rod system. I will do more extensive testing in the near future.
ChicagoTex
04-07-10, 01:40
You and your precious science! Don't you realize the way to win teh internetz is by shouting your armchair-based opinions as loudly as possible with no actual facts to back them up?
[/sarcasm]
Seriously though, once again you've taken the time to gather very useful comparative data that sheds light on the realities of modern weaponcraft; Kudos!
I was especially pleased that you gathered data on bolt temperatures, since piston pushers are forever crowing about how much cooler their bolts are without furnishing actual data...:rolleyes:
Keep up the good work, I check your blog regularly and always enjoy your insight and honesty.
Yes, Thank You for sharing the information.
Until I discovered this site, I was pretty well set on purchasing a Piston AR. The more information I come across regarding the standard DI AR series of rifles it just solidifies my amateur opinion that for many it may just be the best choice of all the ARs currently available, especially considering the availability of standard (non-proprietary) parts.
SkiDevil
good info. you wouldnt happen to have a pencil barrel to test too.
ForTehNguyen
04-07-10, 07:51
yea the bolt temperature myth debunk is also confirmed by another article that was posted a couple weeks ago. They fired a buncha rounds and the guy touched the bolt on purpose without getting burns.
My only suggestion would be to take more data points in that 10 minutes rather than just the four. Maybe every minute instead of these intervals
Thanks for the test.
87, any chance you can take actual chamber temperature measurements?
Im wondering if piston guns tend to have cooler chambers although i highly doubt this is the case since barrels should heat up uniformly whether they're DI or Piston operated.
I find it hilarious that people will bitch about the temperature of the bolt but they will never bitch about the temperature of the piston operating parts. There are more moving parts and springs in a piston gun than there are in a DI gun that are exposed to heat.
ForTehNguyen
04-07-10, 12:44
I have the feeling chamber temps will be very similar if not the same
m24shooter
04-07-10, 19:33
yea the bolt temperature myth debunk is also confirmed by another article that was posted a couple weeks ago. They fired a buncha rounds and the guy touched the bolt on purpose without getting burns.
My only suggestion would be to take more data points in that 10 minutes rather than just the four. Maybe every minute instead of these intervals
Thanks for the test.
Any chance you would have a linky to that discussion?
This myth has always pissed me off. Often perpetuated by liars like LWRC and many other bottom feeding piston peddlers.
Some dude over on Silencertalk made a thermal video of the DI with a silencer mounted. The point was to see how a can heated up. But it was quite interesting and undeniable to see the LACK of heat build up in the bolt group area.
Every gun will eventually get a hot barrel and chamber, but the idiotic myth that the DI is significantly worse is an absurd pile of crap.
This myth has always pissed me off. Often perpetuated by liars like LWRC and many other bottom feeding piston peddlers.
Some dude over on Silencertalk made a thermal video of the DI with a silencer mounted. The point was to see how a can heated up. But it was quite interesting and undeniable to see the LACK of heat build up in the bolt group area.
Every gun will eventually get a hot barrel and chamber, but the idiotic myth that the DI is significantly worse is an absurd pile of crap.
Not going to disagree.
I posed the question not to support what i believe to be largely a myth but to have someone provide some scientific evidence to dispel it.
Mark M is right. LWRC is below bottom feeders. Worse customer service ever! They don't care if you are on a LEO/MIL account. They treat you like crap and they have supervisors that cuss a lot. I counted the LEO supervisor saying G*d D*mn 7 times in one conversation. They are not professional. I will NEVER spend another penny with them. They do not stand behind their products. The piston driven crap is just crap. DI has been working and will still be working. There is a reason why the Big Green Killing Machine has NOT gone to Piston ARs. Now after a couple of thousand in the hole I know why. Do not learn this expensive lesson like I did. LWRC sucks balls.:mad:
I guess my only question is, at what point, or after how many rounds fired does the
" DI's are more dirty than Piston systems" come into play if at all? That seems to be
the other major part of the DI vs Piston comparison.
Unsuppressed DI weapons are without a doubt "dirtier" than piston guns.
The problem lies in the fact that most internet commandos (im one of them) dont do enough high volume shooting to realize just how far you can push the DI system, DIRT AND ALL, with just a little lube.
I think you just discribed my volume of shooting to a T. But for some reason I find myself still wanting a good piston setup. Just thought of another, what about site recovery? I've also read piston guns have less recoil and thus have faster site recovery. Ok, I think I'm done. Thanks for the reply to my question. Didn't mean to step on the thread.
Aurispector
04-07-10, 21:51
Unsuppressed DI weapons are without a doubt "dirtier" than piston guns.
The problem lies in the fact that most internet commandos (im one of them) dont do enough high volume shooting to realize just how far you can push the DI system, DIRT AND ALL, with just a little lube.
Here's a link to an article talking about exactly that. It's all about proper maintenance and understanding how the system is supposed to operate.
http://www.defensereview.com/m4m4a1-carbine-reliability-issues-why-they-occur-and-why-theyre-our-fault/
Thanks again for the reply, and the link.
ChicagoTex
04-07-10, 22:04
what about site recovery? I've also read piston guns have less recoil and thus have faster site recovery.
I've read exactly the opposite.
vicious_cb
04-07-10, 22:19
I think you just discribed my volume of shooting to a T. But for some reason I find myself still wanting a good piston setup. Just thought of another, what about site recovery? I've also read piston guns have less recoil and thus have faster site recovery. Ok, I think I'm done. Thanks for the reply to my question. Didn't mean to step on the thread.
Who told you that BS? Its the that piston will have a sharper recoil impulse. Maybe you heard it wrong.
I think you just discribed my volume of shooting to a T. But for some reason I find myself still wanting a good piston setup. Just thought of another, what about site recovery? I've also read piston guns have less recoil and thus have faster site recovery. Ok, I think I'm done. Thanks for the reply to my question. Didn't mean to step on the thread.
Every piston gun ive ever shot has had a sharper recoil impulse. Beyond being sharp its quite different in the way the recoil feels when compared to an average DI AR.
What i dont understand is what exactly are piston guns supposed to be fixing that is so "broken" with the AR system?
The majority of malfunctions that we see have nothing to do with the actual gun (if its set up properly) and more to do with the magazines and the ammo itself.
I hate to turn every thread into a piston versus DI debate. Im really not a fan of pistons but i have no personal bias against them except when people love to flog them as being the solution to the AR "problem".
No Bananas
04-07-10, 22:45
Thanks to 87GN for the cool study and great info.
I have an Adams Arms Kit on my 10.5" SBR. I have been pleased with it, no malfunctions in over 1400 rounds. I've shot enough rounds through it at one time to get the barrel smoking pretty good. It has always functioned.
I don't have any buffer tube wear from carrier tilt (yet). I did have some wear on the upper from the cam pin. I noticed this at about 1000 rounds and put in the POF roller cam pin. 400 rounds later the wear hasn't gotten any worse. However, because there was wear already there, and because I have shot few rounds (comparatively), I can't really say ,yet, how effective it is.
I do notice less recoil with the AA kit compared to when it was DI. Although most AA users say they have less felt recoil, I can't say if that is really due to the piston system. First, I'm using a heavier buffer with the AA kit. Although AA says their gas block is only 3 oz. heavier than a standard FSB, it feels heavier to me, and the rifle feels more muzzle heavy to me than when it was DI.
The AA kit is much cleaner (on the BCG). No comparison there, in my experience. I have a 12.5" SBR that has about the same number of rounds through it as my AA Kit SBR and the AA kit SBR barely had any carbon build up on the BCG after 1000 rounds. BUT, there is carbon build up where the op-rod vents near the gas block. Had some build up on my folding front sight. I want to note that my 12.5" SBR DI rifle has been just as reliable as my 10.5" SBR w/ AA kit.
My story is similar to others. I fell for a piston ar before I found this site or really dug through objective threads concerning the argued advantages of the piston guns. I'm close to selling it. This thread pretty much sealed the deal for me. I do find it to be very heavy up front, compared to my friends DI ar's. And while my bcg is a breeze to clean, the dirtiness of the rail and fore-end makes up for whatever the "piston carbon savings" provide me. Its a trade off. I'm ready to give DI a try, however. Thanks for the OP.
its an lwrc m6a2 I'm speaking of btw. :/
joshua79109
04-08-10, 12:20
87GN - I like and appreciate your posts and the info you provide - Thanks
I like both DI and piston, so this comment is not meant to state that either is better than the other.
I have only used DI when it mattered and that was while serving in the military.
I currently have a few DI ARs that I fully trust and I also have a piston carbine that I fully trust (SCAR).
I will say a few things that I believe to be true about the piston carbine I have. I like to say up front that this is in comparison to a mid length AR with same barrel length and each has a Vortex FH - each has the same gear attached in the same places.
- better recoil impulse for me - it shows (in time) especially when moving from target to target (quicker and less muzzle jump)
- the bcg (etc...) is less dirty and easier to clean after use than my DI ARs. The piston is very easy to clean and is even easier now that I took someones advice and used Flitz to polish the piston.
- better balance for me
I believe that a person really has to want a piston carbine to pay the dollar asked - since a person could easily build two nice ARs for the price of one piston carbine. It is also my opinion that if a person wants a piston it's better to get away from the AR design altogether to get more benefits such as a folding stock for easier pack /stow, better extractor, etc....
Again - I'm not attempting to state that either the piston or the DI is better. I do find it odd that so many folks dump on the piston when some of our best military weapons (past and present) use a piston system. I also find it odd that so many folks feel that the DI system is in any way inferior - the DI system is well proven.
They're just different. I enjoy each.
I've read exactly the opposite.
me too
Belmont31R
04-08-10, 17:35
DI guns have a piston too. Its called the BCG. A "piston" gun with an op rod and all that just moves the piston from the BCG to above the barrel, and adds parts.
IMO if you want a "piston gun" then buy one setup to be one from the start. Like a SCAR, ACR, Rob Arms, AK, etc.
i have a question that i started to make a thread but it may fit fine here. As far as the "di is dirtier" aspect, has anyone ever had a bcg coated in np3 from robar? wonder if that might help????
i have the abaility right now to shoot a lot when i go shoot i shoot at a min a 1000 rounds through my new ar and it happens to be a di gun ( noveske afghan ) i almost when to the piston route but had the oportunity to shoot one and didnt care for it and the guy that owned it says he hasnt cleaned it in 2k rounds blahblah .... why would you clean your rifle i dont understand i love cleaning mine i enjoy it a lot i buy all sorts of stuff to try out when cleaning and when im shooting ( and all of my shooting is static shooting ie running and clearing home made ipsc/uspsa ranges) none of the slow bench stuff all i do is spray some lube on the bolt and im good to go it worked in iraq for me and its working now i just figured that the piston was a gimicky way to sell guns and take a niche in the market so i ran from lwrc and spent my money elsewhere and am very happy with my new rifle purchase
Thanks for this post. I have read & heard alot of gas piston propaganda, which lead me to believe that piston systems are better. But I refuse to spend twice the money for one, and reading this post offers reassurance. One question I have regarding a minor advantage pistons have over DI is firing water submereged ARs, (although not a common scenario). If I am wrong, please clarify. Regardless, I dont plan on changing my DIs for GPs anytime soon. Thanks guys for the outstanding info on this board, I have learned quite a bit from the pros. here. Thanks!
I have two POF shorty uppers - both M4 handguard versions, not with the heatsink and forerail.
Definitely agree with the OP that with a shorty, a piston adds to reliability. I run them in my M16s, full-auto. Heat may be one thing, but reliability is important. These piston/op rod uppers have been very reliable - probably near 100% over years, mags usually are more of a problem.
Can't say it was that way with my LMT or CMMG DI shorty uppers. If I could get them to run (usual buffer, spring, ammo, bolt tweeks) , inside of 300 rounds they would need cleaning to keep them running.
Belmont31R
04-09-10, 17:51
i have the abaility right now to shoot a lot when i go shoot i shoot at a min a 1000 rounds through my new ar and it happens to be a di gun ( noveske afghan ) i almost when to the piston route but had the oportunity to shoot one and didnt care for it and the guy that owned it says he hasnt cleaned it in 2k rounds blahblah .... why would you clean your rifle i dont understand i love cleaning mine i enjoy it a lot i buy all sorts of stuff to try out when cleaning and when im shooting ( and all of my shooting is static shooting ie running and clearing home made ipsc/uspsa ranges) none of the slow bench stuff all i do is spray some lube on the bolt and im good to go it worked in iraq for me and its working now i just figured that the piston was a gimicky way to sell guns and take a niche in the market so i ran from lwrc and spent my money elsewhere and am very happy with my new rifle purchase
AR's can go a long time without cleaning. Just need to reapply lube every 1k rounds or so, and use something like SLIP EWL which doesn't burn off quickly.
And yes I think much of the propaganda around piston guns is flat out false. What I think they do improve on is using them with a can which means you don't get so much gas back in the face.
Belmont31R
04-09-10, 17:52
Thanks for this post. I have read & heard alot of gas piston propaganda, which lead me to believe that piston systems are better. But I refuse to spend twice the money for one, and reading this post offers reassurance. One question I have regarding a minor advantage pistons have over DI is firing water submereged ARs, (although not a common scenario). If I am wrong, please clarify. Regardless, I dont plan on changing my DIs for GPs anytime soon. Thanks guys for the outstanding info on this board, I have learned quite a bit from the pros. here. Thanks!
Makes no difference because what causes failures with water in the barrel has nothing to do with it being a piston gun or not. A piston gun doesn't defy the laws of physics, and somehow overcome a barrel obstruction.
One question I have regarding a minor advantage pistons have over DI is firing water submereged ARs, (although not a common scenario).
Hammer forged barrels are far more important in that regard. If you are in that situation with a "regular" AR, just let the water drain out of the barrel for 2-3 seconds.
The professed reliability improvement seems to be expressed largely by those marketing the system. While DI has had a number of reports by professionals showing the capability of being shot for 25K + rounds without cleaning, or shooting 2,500 rounds without any lube at all, there isn't anything comparable from the piston camp.
If it works, publish the report. POF claims three years on the carbine competition trail shooting thousands of rounds, so it can't be that hard to take a piston and do the same. Don't clean one, don't lube the other, count the rounds, and tell us about it.
That would be a lot more credible than the allusions about the DI system being like a chicken and it's casual eating habits.
Being indifferent on the topic, does anyone here know much about the Para Ordnance TTR? They bought out a company called ZM, who labeled it as the LR 300 who I'm guessing was the originator of the concept.
Basically, I have just heard about this design and wonder if it has gone through military testing, consideration, etc.
AR's can go a long time without cleaning. Just need to reapply lube every 1k rounds or so, and use something like SLIP EWL which doesn't burn off quickly.
And yes I think much of the propaganda around piston guns is flat out false. What I think they do improve on is using them with a can which means you don't get so much gas back in the face.
They do not.
Either way you're going to be sucking gas. There may be "less" gas coming back in your face but ill be honest...it sucks either way lol.
Being indifferent on the topic, does anyone here know much about the Para Ordnance TTR? They bought out a company called ZM, who labeled it as the LR 300 who I'm guessing was the originator of the concept.
Basically, I have just heard about this design and wonder if it has gone through military testing, consideration, etc.
I have been shooting the ZM Weapons "delayed impingement LR-300 system for over 10 years. I have an early model and 3 of the last ones released before the deal with Para. I like it because of the folding stock. It packs really compact.
As for the DI vs Piston, I love them both. I have my favorite DI rifles and my favorite Piston rifles. I don't have a favorite among all of them. I love them like I love my children. Now as for my go to rifle, that is a topic for another thread.
Regardless of which one you prefer, the piston system has always been the standard until the AR15/M16/M4. Go back to the Sturmgewehr, AK47, FAL, M1 Garand, M14, etc. What is the future? Now we have the SCAR and the Remy/Bush ACR. DI is going to end with the AR and always have it's place. Retrofitting the AR to use a Gas Piston system is innovative. Whether it is needed or not, it has helped to create new piston weapon systems that resemble the AR to some degree or another. The new piston weapon systems have borrowed some of the ergonomics and controls we are all used to on the AR. The modularity of the AR is what has made it so popular, not the DI gas system.
Those of us who enjoy the shooting sports are always looking for the latest and greatest. We are all going to benefit from the R&D done by all the companies putting out so many systems and that leads to new and better weapons in the future. How many people knocked Glocks back in the 80's because it was plastic? Now "plastic" guns are outselling everything else. Who ever thought an old weapon like a revolver could be made of plastic and now we have at least one? Whether you decide to be an early adopter of a new innovation or wait, we all benefit. What holds most of us back from early adoption is cash. If we all had the money, we would buy up everything and run it through it's paces hoping we didn't get a lemon to discourage our experience.
Sorry for the long rant but that is just my opinion. Now I need more $$$ to buy up more good American innovation and give them a shot. Let's hope, pray and vote so that our generation and future generations can continue what our ancestors fought for.
O
Unsuppressed DI weapons are without a doubt "dirtier" than piston guns.
The problem lies in the fact that most internet commandos (im one of them) dont do enough high volume shooting to realize just how far you can push the DI system, DIRT AND ALL, with just a little lube.
I decided to give the 2000 round challenge (http://m4carbine.net/showthread.php?p=523158#post523158) a go with my 14.5" Noveske basic; 1740 rounds with no lube/cleaning and zero issues thus far. I should hit 2000 rounds in the next week; I'll start a thread with more details and pics...
Makes no difference because what causes failures with water in the barrel has nothing to do with it being a piston gun or not. A piston gun doesn't defy the laws of physics, and somehow overcome a barrel obstruction.
I (IMO) understand catastrophic failure involved with firing ARs underwater (gas expansion & volume in the gas tube and bbl) . It was a specific manufacturer which advertised their gas pistons as suited to fire underwater, and demonstrated submerged firing during an on-line commercial. It was the phrase 'strategically placed cuts in the upper receiver which allow the ???? upper to fire submerged w/out catastrophic failure.' When I heard this I was amazed and thought "boy, now I can shoot a gas piston AR underwater". I hope you understand what I mean. Thanks
No Bananas
04-12-10, 22:33
I decided to give the 2000 round challenge (http://m4carbine.net/showthread.php?p=523158#post523158) a go with my 14.5" Noveske basic; 1740 rounds with no lube/cleaning and zero issues thus far. I should hit 2000 rounds in the next week; I'll start a thread with more details and pics...
I want a Noveske:(
Magic_Salad0892
04-12-10, 23:18
I will go ahead and say it now.
I believe the piston operating system is superior (not in every way) to the direct gas impingement system.
Weight - DI > GP
Reliability - DI = GP
Reliability in harsh conditions (Over the beach, mud, dust, neglect, water, etc.) - DI < GP
Balance (Weight distribution) - DI > GP
Accuracy - DI = GP (IMO)
Parts Commonality - DI > GP (No competition.)
Service Life - DI < GP (No competition, IMO. )
Second Kind of Cool - DI = GP (Completely subjective, I want to have pistons in all my guns.)
Overall Neglect (No cleaning OR lubricants) - DI < GP
Short Barreled Rifle Use - DI < GP
Suppressor Use - DI < GP
SPR/Precision Rifle Use - DI > GP (Less reciprocating mass = less recoil = quicker engagement)
Cost - DI > GP (No competition.)
I love the AR-15 platform. I love the piston system. Why can't I have both?
This site, and AR-15.com and numerous other sites seem to be completely anti-piston.
I love the DI system, and have no problem relying on it. I did for a long time before LWRCi and AA came on the scene. I still do, I own a KAC SBR that I run suppressed. It's DI.
There is NOTHING wrong with the DI system, nothing is broken.
But the piston system has less limitation, IMO. I can do things with a piston that I can't with a DI gun.
Everybody says cleaning isn't an issue. This is mostly true.
But, in battle, SHTF, or other scenarios, you don't really know if you can lube, or maintain your rifle. I like knowing that I don't have to think about that.
I run a piston rifle, for the same reason I run a Glock over a 1911.
I like DI guns, but GP systems are massively unappreciated.
I will go ahead and say it now.
I believe the piston operating system is superior (not in every way) to the direct gas impingement system.
Weight - DI > GP
Reliability - DI = GP
Reliability in harsh conditions (Over the beach, mud, dust, neglect, water, etc.) - DI < GP
Balance (Weight distribution) - DI > GP
Accuracy - DI = GP (IMO)
Parts Commonality - DI > GP (No competition.)
Service Life - DI < GP (No competition, IMO. )
Second Kind of Cool - DI = GP (Completely subjective, I want to have pistons in all my guns.)
Overall Neglect (No cleaning OR lubricants) - DI < GP
Short Barreled Rifle Use - DI < GP
Suppressor Use - DI < GP
SPR/Precision Rifle Use - DI > GP (Less reciprocating mass = less recoil = quicker engagement)
Cost - DI > GP (No competition.)
I love the AR-15 platform. I love the piston system. Why can't I have both?
This site, and AR-15.com and numerous other sites seem to be completely anti-piston.
I love the DI system, and have no problem relying on it. I did for a long time before LWRCi and AA came on the scene. I still do, I own a KAC SBR that I run suppressed. It's DI.
There is NOTHING wrong with the DI system, nothing is broken.
But the piston system has less limitation, IMO. I can do things with a piston that I can't with a DI gun.
Everybody says cleaning isn't an issue. This is mostly true.
But, in battle, SHTF, or other scenarios, you don't really know if you can lube, or maintain your rifle. I like knowing that I don't have to think about that.
I run a piston rifle, for the same reason I run a Glock over a 1911.
I like DI guns, but GP systems are massively unappreciated.
I think you attribute a lot of things to items that certain piston/op-rod rifles have, but are not exclusive to piston/op-rod rifles.
For example, the POF RDIK would stay cooler than a Colt M4...the barrel even stayed cooler than the POF P-415.
I might even wager that it stays cooler than (insert your favorite piston gun here).
Nickel Boron or NP3 plating can be applied to any AR. 9310 bolts are usable in any AR. Hammer forged barrels with quality nitriding processes can be used in any AR, and hammer forging is far more important to resisting catastrophic barrel failure due to an obstruction than the simple presence of an op-rod. If it was just the op-rod, then Osprey wouldn't have faked their OTB test.
Put all of those things in a rifle that actually does stay cooler (not just "this system runs cooler, look, I can touch the bolt carrier"), meaning that lube will stick around longer, and parts aren't being subjected to extreme heat or heat cycles, etc, and a lot of the "DI < GP" stuff might go the other way.
I do not remember where i read it.
But, Guy was interviewing Owner of Noveske and he said reason he is not making piston AR is when he tested with his gun and GP rifle with Suppressor on, both of the guns got dirty.
Magic_Salad0892
04-13-10, 00:29
I'm not trying to be rude, I don't know any other way to ask.
What do you think I'm attributing to piston/op-rod guns, that aren't exclusive to them?
The selling points for me on a piston gun, are the ability for me to neglect it, and be able to run it through harsh conditions.
Or just being able to do things that an AK can do, with an AR.
I'm not trying to be rude, I don't know any other way to ask.
What do you think I'm attributing to piston/op-rod guns, that aren't exclusive to them?
The selling points for me on a piston gun, are the ability for me to neglect it, and be able to run it through harsh conditions.
Or just being able to do things that an AK can do, with an AR.
Already mentioned.
Nitriding - theoretically longer barrel life.
FailZero (Nickel Boron) - theoretical reduced requirement for lubrication.
9310 bolt - stronger than other metals. Theoretically longer bolt life.
Hammer forged barrel - theoretically greater accuracy, longer life, etc.
Would you take a piston/op-rod rifle with none of the above over a standard AR-15 with some or all of the above? You say you like LWRC. Unless I'm mistaken, their newest rifles incorporate all of the above. One of the things you mentioned in your first post was longer service life. Every one of the above items contributes in some way, at least theoretically, to longer service life, greater reliability in harsh conditions, etc. And yet every one could be used with a gas tube. I know I'd take a standard AR with the above - assuming everything else was done right - over a gas piston conversion that was designed for profit over performance.
I have done things with my ARs that some think only an AK can do. I did those things to an AK and it choked. Said ARs have gas tubes. Thousands of rounds without cleaning or lubrication beyond round 1? Done. Bury the rifle and mags in dirt with the ejection port cover open and shoot until failure or no more ammunition? Done (By the way, I ran out of ammunition first). And so on...
I do not remember where i read it.
But, Guy was interviewing Owner of Noveske and he said reason he is not making piston AR is when he tested with his gun and GP rifle with Suppressor on, both of the guns got dirty.
I have read the same thing before and have seen it in person if you clean your rifle ( and you should ) then the piston is just a preference with added recoil
Magic_Salad0892
04-13-10, 00:56
Already mentioned.
Nitriding - theoretically longer barrel life.
FailZero (Nickel Boron) - theoretical reduced requirement for lubrication.
9310 bolt - stronger than other metals. Theoretically longer bolt life.
Hammer forged barrel - theoretically greater accuracy, longer life, etc.
Would you take a piston/op-rod rifle with none of the above over a standard AR-15 with some or all of the above? You say you like LWRC. Unless I'm mistaken, their newest rifles incorporate all of the above. One of the things you mentioned in your first post was longer service life. Every one of the above items contributes in some way, at least theoretically, to longer service life, greater reliability in harsh conditions, etc. And yet every one could be used with a gas tube. I know I'd take a standard AR with the above - assuming everything else was done right - over a gas piston conversion that was designed for profit over performance.
I have done things with my ARs that some think only an AK can do. I did those things to an AK and it choked. Said ARs have gas tubes. Thousands of rounds without cleaning or lubrication beyond round 1? Done. Bury the rifle and mags in dirt with the ejection port cover open and shoot until failure or no more ammunition? Done (By the way, I ran out of ammunition first). And so on...
My Good Sir, that was a damn good arguement.
First off though, you can't assume that all piston rifles were made for profit over performance.
H&K (who I don't want to like, but am warming up to,) LWRCi, AA Retrofits, LMT (Kind of...) all do something that is performance over profit. Admittedly most of them do the same thing.
H&K and LWRCi being the ones I think do the same thing. (LWRCi being slightly better, with their amazing stock coated trigger, and NiCorr surface conversion.)
AA being the really cheap option for DI guys who just have to have a piston.
LMT making an excellent monolithic option.
As for the rest of your argument. I don't really have a good reply.
My last argument being, this isn't a factor for most people, but being that I live right near the coast, it's a factor for me.
Over the beach is a bit safer with most piston rifles. I also like having the option to completely turn off the gas in my rifle, making suppressor use quieter, or just having a bolt gun, and an auto-loader in the same platform.
ETA: I don't really know if this is an advantage to the piston, because you certainly pay for it, but pistons don't erode, and need to be replaced like gas tubes (a whole $13) do. Just thought I might add that.
I don't really know if this is an advantage to the piston, because you certainly pay for it, but pistons don't erode, and need to be replaced like gas tubes (a whole $13) do. Just thought I might add that.
This is what you chose to finish with? really?
One of our shooters has a carbine with well over 10k, maybe even 20k rounds through it and he recently re-barreled it. They replaced the gas tube just because they could, and it was FINE. In fact, they made up a little wire jig to scrape the inside of it to "clean" it and nothing of consequence came out! If the gas tube can outlast the barrel itself, well....
I have a question. If so many of us stress the importance of having a free floated rail and a H-Bar or thicker profile barrel, why would we chose a piston system? We spend the extra cash to get the free floated setup then add a piston on top of the barrel to move back and forth to mess that whole free float thing up. I feel like the companies out there are just selling ARs on a new gimmick. I would like to see someone with more knowledge and funds do a test to see if what I think is true. I know that the LWRC 6.8spc I paid top dollar for shoots like an AK. Hell, I have a bushmaster that is more accurate. That is sad, considering Bushmaster is not top tier and I paid almost a third for it. Now the LWRC does go bang every time, but then so does the Bushy......
My Good Sir, that was a damn good arguement.
First off though, you can't assume that all piston rifles were made for profit over performance.
H&K (who I don't want to like, but am warming up to,) LWRCi, AA Retrofits, LMT (Kind of...) all do something that is performance over profit. Admittedly most of them do the same thing.
H&K and LWRCi being the ones I think do the same thing. (LWRCi being slightly better, with their amazing stock coated trigger, and NiCorr surface conversion.)
AA being the really cheap option for DI guys who just have to have a piston.
LMT making an excellent monolithic option.
As for the rest of your argument. I don't really have a good reply.
My last argument being, this isn't a factor for most people, but being that I live right near the coast, it's a factor for me.
Over the beach is a bit safer with most piston rifles. I also like having the option to completely turn off the gas in my rifle, making suppressor use quieter, or just having a bolt gun, and an auto-loader in the same platform.
ETA: I don't really know if this is an advantage to the piston, because you certainly pay for it, but pistons don't erode, and need to be replaced like gas tubes (a whole $13) do. Just thought I might add that.
I don't think all piston manufacturers put profit over performance. I was mainly angling for the conversions there, but there are a few complete piston rifle companies that I wouldn't touch either (CMMG, for example).
Again, unless your rifles have hammer forged barrels, it doesn't matter whether they have an op-rod or a gas tube - they will most likely blow up if you try to shoot with an obstructed bore. As I said before, Osprey Defense wouldn't have had to put duct tape over the muzzle of the rifle they were "testing" if the simple addition of an op-rod to the AR-15 prevents failure in an OTB test. Their logic after being "caught" was...interesting.
I've seen several hammer forged barrels survive incidents that would have destroyed standard barrels recently. Both were rifles that were fired with obstructed bores, and they remained functional, although they had slight bulges in the barrel and became quite inaccurate.
Magic_Salad0892
04-13-10, 15:27
First off, I didn't say the gas tube thing was a real advantage. Lol. just something I threw in there.
Yeah, DI guns can stand up to most things a piston gun can, but as I mentioned before (I think) I'd just feel more comfortable in harsh environments with a piston driven rifle. (LWRCi, H&K, I'd love it if Daniel Defence did one.)
Overall I love both, but I prefer the piston operating system.
Like I said before. I love pistons, I love ARs. Why can't I have both? ... Now I can. :D
(You're also right, in not wanting to even be remotely near a CMMG piston gun.
Personally I wont go near CMMG, Ruger, and for a while I wouldn't touch Stag either.
But I shot the stag, and I kinda like it. I'd never buy one, but it's a good budget piston gun.
BTW: Ironfins. Can you post pictures of these targets you shot with your LWRCi?
I'm starting to think you just hate them/piston guns for no real reason. In every thread about piston guns, or LWRCi, or where they're mentioned you're always quick to bash them down. You're also the only person I've ever heard with these issues. Can you back any of this up?
Yes I can salad, BTW, they kept my owners manual, gun oil, and magpul accessory pack that came with the rifle. They told me to ship everything so I did. I was told by Joe that he would ship them back to me ASAP over a week ago. I was told today when I called at 8am I would get a call back to let me know when to expect them. At 5 mins before they close I had to call them and was informed "Joe has been busy setting up for a open house, he hasn't shipped them yet buy will this afternoon, he works late." No surprise here, another LWRCi blunder.
<a href="http://s658.photobucket.com/albums/uu306/IRONFINS/?action=view¤t=IMG_3157.jpg" target="_blank"><img src="http://i658.photobucket.com/albums/uu306/IRONFINS/IMG_3157.jpg" border="0" alt="Photobucket"></a>
http://i658.photobucket.com/albums/uu306/IRONFINS/th_IMG_3160.jpg (http://s658.photobucket.com/albums/uu306/IRONFINS/?action=view¤t=IMG_3160.jpg)
http://i658.photobucket.com/albums/uu306/IRONFINS/th_IMG_3162.jpg (http://s658.photobucket.com/albums/uu306/IRONFINS/?action=view¤t=IMG_3162.jpg)
http://i658.photobucket.com/albums/uu306/IRONFINS/th_IMG_3163.jpg (http://s658.photobucket.com/albums/uu306/IRONFINS/?action=view¤t=IMG_3163.jpg)
Now keep in mind that these are at only 50 yards with an optic. I was told when purchasing that it should shoot under 2 inch groups at 100 yards, but most shoot under 1 inch at 100 yards. My groups were at 6 inches at 100 yards, and 4 inches at 75 yards. Didn't take photos of the embarrassing targets I shot. I also didn't appreciate the poor quality of customer service. A manager should NOT cuss every other word, that is why I am not giving this rifle another chance, I am done with LWRCi. Not what I call a professional company when dealing with problems.
Ironfins (and others) thanks for sharing your experience that really helps me avoid future disappointment and unreliable equipment. I appreciate the information posted and I try to learn from others info & misfortune. Posts like this change my course of thinking, instead of a piston AR, I bought a LMT M4 last month and so far its been 100% reliable. Instead of the B.S. hype and propaganda created by the manufacturer, I read the posts written by unbiased individuals that run these ARs unmercifully thru the paces to gain knowledge of what works. So thanks guys for saving me from headaches!
Magic_Salad0892
04-13-10, 20:36
Are you sure it's the rifle?
How's the trigger? Optic? You?
Thank you onado2000, I have only posted my findings to help others. Most people just want to argue that they are so great. But when asked if they want to buy mine cheaper than they could ever find one for they all of a sudden don't need one or don't have money. Too many people are full of crap on these forums and I am thinking of stop posting stuff to try to help. I only post what I know for fact, not what I have heard, or what a "Internet Ranger" told me. Being in LEO we generally don't make a lot of money, especially to try new "toys". So when my money is spent, it is usually a good purchase. I researched LWRCi, for a long time and fell into the hype, I sold another AR that was accurate and saved up the rest for this M6a2 and it was an absolute failure in performance for the price. I just hope other people don't waste their time, and if you search long and hard you'll find other people complaining about LWRC. If someone pays upwards of $2500.00+ for an assault rifle, it should out perform all others less than it. I plan on taking a loss on the rifle. I hope this weekend I will sale or trade it at the gun show, but I will inform the new owner of my situation and provide these targets. Someone out there with more money to shoot several different kinds of ammo and probably reloads and find what works best I guess. I just don't think I should have to use a $1500.00 optic to get a $2500.00 gun to shoot. People, save your money and buy a Noveske, BCM, DD, or LMT. There is a reason that the M-16 has been around for 45+ and has stayed Direct Impingement. Why pay a lot of money for a free floated barrel and rail when you add a bouncing piston on top of the barrel which effects the point of impact. Piston may work in other platforms, but I haven't seen a great improvement worth paying almost 3 times what a decent AR costs. Just my thoughts.........
...the title is meant to be in jest, by the way. http://vuurwapenblog.com/2010/04/04/heat-dissipation-two-schools-of-thought/
----
Heat is discussed fairly often on various internet forums, especially when two subjects come up: barrel profile and method of operation.
We often see comments about how light barrels heat up too quickly. This is partially true – a lighter barrel will generally heat up faster than a heavy barrel. The “too” part is where the problem lies. Too fast for a machine gun barrel? Most likely. When you’re putting out a sustained rate of fire that can reach several hundred rounds per minute, a light barrel is definitely unsatisfactory. However, if you have a rifle, and not a machine gun, a lighter profile barrel may not heat up “too quickly”.
Also, there are many comments about how cool piston/op-rod systems run. I’ve never found touching the bolt carrier after firing to be a necessary exercise, but some find it to be very important, or at least fun. However, it’s not as if the presence of the op-rod has a chilling effect on the barrel, which is a critical component of the rifle, to be sure.
So we have two schools of thought here: that a lightweight barrel profile is more appropriate for use on a carbine, and that the standard system of operation is not unnecessarily hot; and that a heavy (or fluted/heavy) barrel is more appropriate for use on a carbine (or maybe a carbine machine gun to be used for laying down suppressive fire), and that an op-rod allows the rifle to run cooler.
Recently, while doing some experiments with standard plastic handguards, I thought I’d also compare a civilian legal M4 clone, or close to it – a Spike’s Tactical M4 LE with a Knight’s Armament M4 RAS handguard – with two Patriot Ordnance Factory rifles. One is a P-415, which uses POF’s op-rod system, and the other is called the RDIK, and it uses a gas tube, just like a standard AR-15. However, it’s equipped with the same heavy fluted barrel, heat sink gas block, reinforced upper receiver, and single piece railed forend that the P-415 uses.
To complete this test, I fired 30 rounds of 5.56mm ammunition through each rifle, then measured the temperature of the handguards in four separate places, as well as the temperature of the gas block/barrel. I measured these temperatures immediately after firing, 1 minute after firing, 5 minutes after firing, and 10 minutes after firing, using an infrared thermometer. I also measured the temperature of the bolt face immediately after firing.
Here are the handguard temperatures:
http://www.545ar.com/heataveragevs.jpg
Note that all three handguards got progressively hotter until sometime after the 5 minute mark. I found it interesting that the POF gas tube upper was within several degrees – up or down – of the P-415 op-rod upper during the whole exercise. I also found it interesting that every handguard had reached essentially the same temperature 10 minutes after firing.
Here are the gas block/barrel temperatures.
http://www.545ar.com/heatGBvs.jpg
I was shocked – honestly – to see how cool the POF RDIK gas block was after firing. There was a greater initial temperature difference between it and the P-415 gas block than there was between the P-415 and the Spike’s M4 LE. In addition, the M4 cooled faster than the P-415, as you can see, though each upper had roughly the same temperature loss profile after 1 minute.
This proves an often-overlooked point: while light barrels do heat up faster than heavy barrels, they also cool down faster than heavy barrels – apparently, faster than even a heavy fluted barrel. This also proves true a comment made to me by an industry professional while we were discussing this topic: that the gas block of a piston/op-rod rifle gets very, very hot.
As a side note, the temperature of the M4’s bolt immediately after firing was 94 degrees; the P-415’s bolt temperature was 88 degrees. The RDIK’s bolt was 89 degrees.
Although this was a very limited and rather unscientific test, it would seem that the vast majority of the POF rifles’ cooling ability comes from the heat sink barrel nut, handguard, fluting, etc, and not from the piston/op-rod system. I will do more extensive testing in the near future.
Very interesting findings.
When debating between a light barrel & heavy barrel for heat, don't forget about the laws of thermodynamics. The heavier barrel has more mass than the lighter barrel. Heat isn't temperature, it's BTUs, or British Thermal Units. Applying the same amount of BTUs to a light barrel as to a heavier barrel, the lighter barrel will have a higher temperature.
What causes damage to a barrel is a change of state. It's easier to change the form of steel when it's in it's plastic state than when it's solid because it's softer. Steel becomes plastic at the same temperature whether you have 1 pound or 10. What does change is the number of BTUs needed to raise the temperature of 1 pound of steel to it's plastic state versus 10 pounds. Just like water. At sea level, water boils at 212 degrees F. It takes longer to boil a gallon of water than a cup because a gallon of water must absorb more BTUs before it reaches 212 degrees.
A heavier barrel will take more BTUs to reach the same temperature, will resist damage from prolonged firing better and will have more BTUs to dissipate before returning to room temperature than a light barrel.
This is not to say that a heavier barrel is always better than a light one. Like everything else, there are trade-offs. One could build a barrel so heavy it'd stay cool for thousands of rounds. But then who but Hercules could carry it?
Magic_Salad0892
04-14-10, 02:33
Ironfins.
I know that if you dug deep (very deep) you'd find people who were unsatisfied by their LWRCi rifle, but compare them to all the other people who run them and love them. Look at their materials and manufacturing process. They are by far one of the best (IMHO the best) options for an amazing quality AR platform that can perform and keep performing. Even if you don't like pistons, they're an amazing rifle. If you're willing to pay to play.
I'm sure somebody will buy it off of you, but I own 3 LWRCi uppers, and 1 full rifle.
M6A3 - 5.56
M6A3 - 6.8 (Full rifle)
M6A2 - 6.8
M6 - 5.56 (Going into Mk. 18 Mod. 1 build.)
I really don't need another.
FWIW, I shoot 1.5-2 MOA w/ my LWRC M6A3 14.7"bbl with ACOG Ta01. Don't have the target, but it was slightly bigger than a quarter. I am by no means a good shot, so it may be the optic set up you had, a defective part, or something else.
This whole debate is funny.
Some people like piston driven AR's simply because its piston driven....its something new and therefore it must be better.....or something like that.
Then there are those that hate piston driven systems simply because they are pistons. They are new and because of that they hate them.
Ive got both, I like both.
Very interesting findings.
When debating between a light barrel & heavy barrel for heat, don't forget about the laws of thermodynamics. The heavier barrel has more mass than the lighter barrel. Heat isn't temperature, it's BTUs, or British Thermal Units. Applying the same amount of BTUs to a light barrel as to a heavier barrel, the lighter barrel will have a higher temperature.
What causes damage to a barrel is a change of state. It's easier to change the form of steel when it's in it's plastic state than when it's solid because it's softer. Steel becomes plastic at the same temperature whether you have 1 pound or 10. What does change is the number of BTUs needed to raise the temperature of 1 pound of steel to it's plastic state versus 10 pounds. Just like water. At sea level, water boils at 212 degrees F. It takes longer to boil a gallon of water than a cup because a gallon of water must absorb more BTUs before it reaches 212 degrees.
A heavier barrel will take more BTUs to reach the same temperature, will resist damage from prolonged firing better and will have more BTUs to dissipate before returning to room temperature than a light barrel.
This is not to say that a heavier barrel is always better than a light one. Like everything else, there are trade-offs. One could build a barrel so heavy it'd stay cool for thousands of rounds. But then who but Hercules could carry it?
My physics knowledge is definitely not the greatest. ;) If you think I should rewrite/rephrase anything, let me know.
I have read in other (that is, real) studies that CMV barrels fail at the same temperature - 1600-1700F - regardless of weight, as you said.
Magic_Salad0892
04-14-10, 14:21
''Some people like piston driven AR's simply because its piston driven....its something new and therefore it must be better.....or something like that.''
I love AR-15s. I've been shooting them for years.
I love pistons because I was raised around and have shot many AKs, G3 clones, FAL clones, bullpups, etc.
I've always been around piston guns. I just prefer the system. In my opinion it's more efficient.
I also like having the upper receiver cleaner in the bolt area, and there being less heat around critical parts. It brings a bit of piece of mind.
I don't bash other peoples opinions that DI is better, but I posted here, because so many people seem to hate piston guns for NO reason. I suspect they also hate AKs, and the like.
I do enjoy the DI system, though.
Magic_Salad0892
04-14-10, 14:23
FWIW, I shoot 1.5-2 MOA w/ my LWRC M6A3 14.7"bbl with ACOG Ta01. Don't have the target, but it was slightly bigger than a quarter. I am by no means a good shot, so it may be the optic set up you had, a defective part, or something else.
Good shit. :)
I'm getting sub MOA with my ACOG in 6.8.
Strong work! You just saved me the cost of a good IR thermometer.
ChicagoTex
04-14-10, 16:13
I also like having the upper receiver cleaner in the bolt area, and there being less heat around critical parts. It brings a bit of piece of mind.
Quoted from original article:
As a side note, the temperature of the M4’s bolt immediately after firing was 94 degrees; the P-415’s bolt temperature was 88 degrees. The RDIK’s bolt was 89 degrees.
The only piece(SIC) of mind is in your mind.
Magic_Salad0892
04-14-10, 17:28
^^ Still a little less temperature, if only by a few degrees.
Odd things is, that I have done a mag dump or two and immediately afterwards, removed my bolt carrier, and it was only a little warm.
That isn't piston propaganda this is something I have personally done myself.
I tried that with a suppressor though...
that was bad. :(
so many people seem to hate piston guns for NO reason. I suspect they also hate AKs, and the like.
The gun that resides under my desk every day is a VZ-58, I think highly of the P-415 that POF gave me and I just bought an Arsenal AK today. :)
Just so everybody is clear, those were not the targets I shot. Nor the ones my friend shot who has a Bushmaster 6.8 that will out shoot this LWRC hands down, sorry but it does. Those targets come from LWRC from two different people at the company that shot it. They told me they used a 4x ACOG and rested it on sandbags while laying prone at 50 yards. So if you are wondering about the optic, trigger, etc. You'll have to ask them. I was planning on mounting a leupold for some more trial runs, but after dealing with LWRC and their horrible Customer Service, I have decided I would rather have a sling shot and some rocks then mess with them.
ChicagoTex
04-14-10, 18:58
^^ Still a little less temperature, if only by a few degrees.
You're seriously arguing to me that parts that have a ~1000 deg failure point really benefit from running SIX degrees cooler?
Now you're just grasping at straws.
You're seriously arguing to me that parts that have a ~1000 deg failure point really benefit from running SIX degrees cooler?
Now you're just grasping at straws.
It's 30 rounds. Could there be a bigger gap in bolt face temp as the firing schedule is made harsher? Maybe. Maybe not. Do we have a control on how fast the rate of fire was? Well, not really, simply that 30 rounds were fired, then the heat was measured.
It's 30 rounds. Could there be a bigger gap in bolt face temp as the firing schedule is made harsher? Maybe. Maybe not. Do we have a control on how fast the rate of fire was? Well, not really, simply that 30 rounds were fired, then the heat was measured.
Sorry, I failed to mention that. They were all mag dumps as quick as I could pull the trigger. I limited this to 30 rounds because the RDIK barrel is in the white CMV with no heat treatment or anything. Don't want to kill the barrel. It's going back to POF to be nitrided, etc and then I can do more stuff with it.
My physics knowledge is definitely not the greatest. ;) If you think I should rewrite/rephrase anything, let me know.
I have read in other (that is, real) studies that CMV barrels fail at the same temperature - 1600-1700F - regardless of weight, as you said.Oh Hell's Bells! I'm just an Aviation Airframe & Power Plant Technician. As such, I've been exposed to a smattering of this & that. Dad said if you can't dazzled them with brilliance, baffle them with, well...Wolf Sign if you get my drift. Since I was fresh out of dazzle...
What you wrote was fine. Forgive me if it sounded like I was critical. I guess I need to work on my phrasing
(Amazing how fast the thread devolved into a "Did too!" "Did not!" of the Piston vs DI kind, isn't it?)
Magic_Salad0892
04-15-10, 00:36
The gun that resides under my desk every day is a VZ-58, I think highly of the P-415 that POF gave me and I just bought an Arsenal AK today. :)
I'm glad that you're satisfied with your POF.
I wasn't saying you hate GP rifles, I was saying that a lot of guys here do, IMO.
http://i850.photobucket.com/albums/ab70/JonathonQuill/Internet-Dont_worry_sir-1.jpg
Found this on another forum, made me laugh.
This myth has always pissed me off. Often perpetuated by liars like LWRC and many other bottom feeding piston peddlers.
Some dude over on Silencertalk made a thermal video of the DI with a silencer mounted. The point was to see how a can heated up. But it was quite interesting and undeniable to see the LACK of heat build up in the bolt group area.
Every gun will eventually get a hot barrel and chamber, but the idiotic myth that the DI is significantly worse is an absurd pile of crap.
Hit the proverbial head on the nail...
Weight - DI > GP
Reliability - DI = GP
Reliability in harsh conditions (Over the beach, mud, dust, neglect, water, etc.) - DI < GP
Balance (Weight distribution) - DI > GP
Accuracy - DI = GP (IMO)
Parts Commonality - DI > GP (No competition.)
Service Life - DI < GP (No competition, IMO. )
Second Kind of Cool - DI = GP (Completely subjective, I want to have pistons in all my guns.)
Overall Neglect (No cleaning OR lubricants) - DI < GP
Short Barreled Rifle Use - DI < GP
Suppressor Use - DI < GP
SPR/Precision Rifle Use - DI > GP (Less reciprocating mass = less recoil = quicker engagement)
Cost - DI > GP (No competition.)
I think this is the kind of popular analysis that has been the historical basis for not liking the DI system for decades. The issue is that all the piston guns used by the valiant heroes of WWII and Korea couldn't possibly be jammomatics.
That's a myth left out of the few conversations that the Greatest Generation ever shared with the Baby Boomers. The assumption that piston guns are more reliable, have less issues, better service life, are more abuse resistant, etc has little to no documentation available. It's just all on the word of a generation who didn't complain about the job they were given and did the best with what they had.
Conversely, the history of the introduction of the M16, and the directly associated end results of Vietnam have been linked together - with beliefs that go beyond the simple facts. One did not create the other, and in fact, had much better results in the hands of American soldiers than was expected - unlike the leadership and command chain.
Reprint the First Article tests of piston guns and DI and compare the results side by side. It's my belief they have gotten a lot tougher over the last 80 years, protocols are much more precisely spelled out, and oversight has increased exponentially. The concept of public scrutiny over a government contract has brought this about, and always had a significant impact.
Look at the second set of "sand tests," and the much less publicized results show DI and piston ran a lot closer. What is lacking in the analysis is also what features besides DI or piston might be contributing to stoppages.
I like the point of this thread - it directly opposes a commonly held misconception about DI and refutes the notion that the bolt carrier group must be getting too hot to operate properly. The stubborn fact is that the bolt carrier isn't getting significantly hotter, and DI isn't the hobgoblin of failure many vested interests are pushing to demonize.
Like i posted on other threads,
i was really close to get Noveske, but then this thread scared me little. lol
however, i will only use it for target, fun, possible future training.
so i dont know.....
Thomas M-4
04-17-10, 09:18
Skang How in the world has this thread scared you from getting a Novoske.
The DI gas system is proven operating system kill-en thousands of dirt bags globally for the past 50++ years. Have you seen the colt barrel test were the keep firing mag after mag FA until the damn barrel droops :eek: and no a gas piston would NOT have helped the barrel. The only combat tested operating systems are the DI system and the HK416.
nothing to fret over Skang - Noveske rifles can hold their own (http://m4carbine.net/showthread.php?t=51936)...
ForTehNguyen
04-17-10, 09:44
barrel heat comes from the friction of the fired round anyways, changing the gas system wont get around this fact
barrel heat comes from the friction of the fired round anyways, changing the gas system wont get around this fact
O rly? How about that whole combustion of propellant thingy?
Friction?
Puhleese.
And, yes, a firearm is a heat pump. The type of action cannot change the amount of heat produced. Though an open bolt will cool faster than a closed bolt system.
O rly? How about that whole combustion of propellant thingy?
Friction?
Puhleese.
And, yes, a firearm is a heat pump. The type of action cannot change the amount of heat produced. Though an open bolt will cool faster than a closed bolt system.
Propellant adds very little to heat build up. Friction is the main cause of heat, period.
Propellant adds very little to heat build up. Friction is the main cause of heat, period.
I "think" I might've just learned something new. You got some links to data? :)
ForTehNguyen
04-17-10, 22:55
O rly? How about that whole combustion of propellant thingy?
Friction?
Puhleese.
look how fast the barrel temperature rises, look how slow the bolt and chamber rise. Its quite obvious that the heat is coming from the friction of the bullet moving down the barrel, especially when the chamber and bolt face are half the temperature of the barrel, despite the bolt face and chamber is where the propellant is combusted. Because the chamber/bolt heat up much slower than the barrel its not combustion that is increasing the temperature. Its bullet friction
http://m4carbine.net/showthread.php?t=51936
look how fast the barrel temperature rises, look how slow the bolt and chamber rise. Its quite obvious that the heat is coming from the friction of the bullet moving down the barrel, especially when the chamber and bolt face are half the temperature of the barrel, despite the bolt face and chamber is where the propellant is combusted. Because the chamber/bolt heat up much slower than the barrel its not combustion that is increasing the temperature. Its bullet friction
http://m4carbine.net/showthread.php?t=51936
The barrel heats up quicker because much more surface of the barrel is exposed to heat than the surface of the bolt. The brass, which is part of the combustion chamber is hot enough to burn skin and it's exposed to very little friction.
The energy released from the burning gasses is greater than the energy absorbed by parasitic drag. Otherwise the bullet would never exit the muzzle. That means more BTUs are generated during firing than from the friction.
The temperatures generated during the firing sequence is high enough to melt steel. You will not generate that kind of heat from the friction of a copper clad or lead bullet down the barrel of a firearm
Magic_Salad0892
04-18-10, 14:15
The only combat tested operating systems are the DI system and the HK416.
The 416 is a gas piston...
Are you saying the only combat tested operating systems ever?
What about G36, AK-47, FAL, G3, etc.?
i guess he meant, far as AR-Style. :D
The barrel heats up quicker because much more surface of the barrel is exposed to heat than the surface of the bolt. The brass, which is part of the combustion chamber is hot enough to burn skin and it's exposed to very little friction.
The energy released from the burning gasses is greater than the energy absorbed by parasitic drag. Otherwise the bullet would never exit the muzzle. That means more BTUs are generated during firing than from the friction.
The temperatures generated during the firing sequence is high enough to melt steel. You will not generate that kind of heat from the friction of a copper clad or lead bullet down the barrel of a firearm
This makes a hell of a lot more sense than bullet friction, especially when you consider the heat after firing blanks.
Magic_Salad0892
04-18-10, 15:19
i guess he meant, far as AR-Style. :D
:) I was just giving him shit for a poorly worded sentence.
ForTehNguyen
04-18-10, 17:41
Heres some quantization, its for a BAR but should be able to assume its pretty similar for an AR platform:
http://www.thehighroad.org/showthread.php?t=313458
Source = Hatcher's Notebook
Army ordinance tests of a 30-06 in a BAR found that only 29 1/4% of the powders energy is transfered to the bullet.
The other 70 3/4% is heat loss.
Broken down:
Heat to brass case = 131.0 calories.
Kinetic energy to bullet = 885.3 calories.
Kinetic energy to gases = 569.1 calories.
Heat to gun barrel = 679.9 calories.
Heat in exhausted gases = 598.6 calories.
Total from powder charge & primer = 2,864.0 calories.
Additional heat generated by bullet friction = 212.0 calories.
Total of one shot of 30-06 ammo = 3,076 calories.
dang we need more efficient guns, losing a lot of energy in waste heat. My statement about friction is incorrect in saying most of the heat came from friction, but its still close to a 1/3 of the heat transferred to the barrel. DI/GP doesn't matter, neither of these get around the heat transfer of combustion gases and heat transfer to barrel.
...DI/GP doesn't matter, neither of these get around the heat transfer of combustion gases and heat transfer to barrel.You may be right. However, in a DI system the gasses are bled off into the gas tube. Heat is carried with these gasses away from the barrel and vented into the action to be absorbed by the parts and the surrounding air.
The piston system vents it's gasses near the gas block which is near the barrel.
In theory, all else being equal, the gasses of the DI system might be cooler when vented into the action than the gasses of the piston system vented at the gas block.
However, it's possible to design the vent to cool the gasses. Venting the high pressure gasses into a low pressure system causes the temperature of the gasses to drop.
Engineers have devised some pretty clever ways to contain thousands of degrees of heat without melting precisely made parts. The heat in the burn section of the PT6 turbine engine is kept away from the thin walls of the burn chamber by high pressure air.
The piston system keeps heated and dirty gasses away from the receiver. However, it's added mass can introduce harmonics that negatively effect accuracy. It also increases reciprocating mass which can increase wear.
The DI system has less mass and has been found to be inherently more accurate than the piston system. However, it vents it's gasses into the receiver, increasing heat and soot in that area. It cooks off necessary lubricants. It also bring high pressure gasses closer to the shooter's face.
The biggest reason soot is a problem with the DI system is the gunpowder. Ball type powder has better flow from the powder thrower and into the case, especially with the small neck of the 5.56. But it's disadvantage is you cannot use the surface of the kernel to control burn rate. With log powder, burn rate is controlled by how much surface you expose to the flame front. Outside diameter, inside diameter and length of the individual kernels of log powder are very important.
Ball powder has to use a graphite coating to retard burn rate and it leaves a nasty residue. Slow burning Winchester ball powders are well none for being dirty.
When Stoner designed the AR, it was to use the much cleaner burning log powder. McNamara and his Whiz Kids decreed that the powder be switched to ball type which left a gummy residue which led to malfunctions. Most piston systems are less sensitive to powder residue.
Stoner hyped the new rifle as self cleaning. That would have been true only using the clean burning log type powders. Piston systems are generally less sensitive to powder residue.
The Swedish Lungman uses a DI system. The difference between it and the AR is the receiver of the Lungman isn't enclosed to trap heat and residue from the exhaust gasses. It also didn't last as long.
When reading advertising claims, remember- Emptor caveat
Heres some quantization, its for a BAR but should be able to assume its pretty similar for an AR platform:
http://www.thehighroad.org/showthread.php?t=313458
dang we need more efficient guns, losing a lot of energy in waste heat. My statement about friction is incorrect in saying most of the heat came from friction, but its still close to a 1/3 of the heat transferred to the barrel. DI/GP doesn't matter, neither of these get around the heat transfer of combustion gases and heat transfer to barrel.
I think your going down a pointless road here. Guns get hot because the requirements of a cartidge are to use a small mass of propellant to create high pressures to propel an object down a tube at a high rate of speed. Using chemical potential energy in a combustion reaction to create kinetic energy and hoping to get the most mechanical energy you can out of it. The second law of thermodynamis says that an isolated system will not decrease its entropy but it will increse its entropy as exergy works its way towards zero. In laymens terms it says that 100% efficiency is impossible, there will always be energy losses. The energy losses in a gunshot are not just heat but sound and light too. The amount of energy lost in the latter two is negligable to that of thermal losses but the point is that they will always be present. It would be better to concentrate your focus on how to get the heat away from the barrel rather than worry about the thermal energy you are losing.
If you want to get more efficiency out of a thermodynamic system you want to get it really hot. Increasing the difference between the highest and lowest temperatures in the system raises the Carnot effeciency which is the highest efficiency possible in the system. The problem is we are limited by materials. A chamber will only take so much pressure and a steel barrel can only get so hot before we start deforming them.
Thomas M-4
04-18-10, 22:25
The 416 is a gas piston...
Are you saying the only combat tested operating systems ever?
What about G36, AK-47, FAL, G3, etc.?
No the only combat proven gas piston AR.
Magic_Salad0892
04-19-10, 03:16
After seeing what they can do, POF and LWRCi are just as tested, and have been around longer.
POF's advantage over the H&K being that it's cheaper, with awesome CS.
Disadvantage being that it's heavier, not as reliable (Still really reliable though, also the cam pin roller is awesome.) and the rail system is REALLY ugly, and heavy.
H&K's advantage over POF - everything else IMO.
H&Ks and LWRCi guns are equal IMO, for different reasons.
Weight - H&K > LWRCi
Accuracy - H&K < LWRCi
Reliability - H&K - LWRCi (Except that LWRCi didn't tamper with their OTB promotion video.)
Innovation - H&K < LWRCi (First RELIABLE self regulating piston system. IMHO.)
ok, I got confused.....is the ford better or is the chevy still king?
ok, I got confused.....is the ford better or is the chevy still king?
You know, this was actually a very informative thread. Your snarky post indicates that you lack the intellectual ability to understand why it was. Maybe that means that ARFCOM might be more your speed, sir.
Magic_Salad0892
05-01-10, 04:56
I take my comment on LWRCi's gun being just as reliable as H&K's gun.
The H&K 416 has problems in very cold temperatures, whereas the LWRCi has had no such problems.
http://www.thefirearmblog.com/blog/2009/03/06/norwegian-soldiers-having-problems-with-hk416-2/
Take it for what it's worth, but it's not the first I've heard of this.
I still really want one though. (I want the 417 more though. :))
You know, this was actually a very informative thread. Your snarky post indicates that you lack the intellectual ability to understand why it was. Maybe that means that ARFCOM might be more your speed, sir.
not really, your snarky post shows that you lack a sense of humor, maybe you'd be more at home at poleupyourass.com.... I learn, trust me but I am a smart ass at heart and tend to try to lighten things up a bit. If you don't like that put me on ignore! If this is the type of forum that cant take a little humor now and then maybe Ill be better served just reading and not posting. But hey, thanks for chiming in and letting me know how intelligent you are!
I did learn a lot from this thread, but i find it funny how in so many different hobbies I have ventured in to over the years there always seems to be some type of debate going on, Ford vs chevy, 2 stroke vs 4 stroke, electric vs mechanical, brushed vs brushless.
the truth of the matter is that none seem better than the other just different and that seems the case here as well but often you get pin heads that dont want to see the other side of things and claim the one they own is king.
me, I am the type that will get both. Ill probably get a psd in 6.8 and then pick up a DI down the road a bit in 5.56.
ChicagoTex
05-01-10, 06:50
Ford vs chevy
Chevy
2 stroke vs 4 stroke
4 stroke
electric vs mechanical
mechanical
brushed vs brushless
brushed
:D;)
And on AR's I'll go DI every time, but that doesn't mean I'm not interested in piston rifles that are similar to the AR. For example, the ACR has piqued my interest with it's accuracy.
in a DI system the gasses are bled off into the gas tube. Heat is carried with these gasses away from the barrel and vented into the action to be absorbed by the parts and the surrounding air.
Not wrong, the common belief that the gasses are released into the action by the gas tube, not so much.
The gas is delivered to the bolt carrier and vented out the two holes in it that face the ejection port. The bolt unlocks, and about the same time the key clears the gas tube, the brass is being retracted out the chamber.
Gas being metered through a .063 hole in the barrel is going to be a much smaller volume than the gas being exhausted past the brass into the chamber and action. All gas action semi's do this, the maintenance manuals are very specific about cleaning residue out of the chamber.
I don't have a non contact thermometer, but I suspect that semi auto brass stays hotter than bolt action. Two reasons, it's bathed in gas as it's extracted, and it doesn't get to transfer it to the chamber as the dwell time is pretty short. A bolt action can hold it's brass for a long as the operator wants.
It's a common misconception that the gas tube dumps a lot of gas into the action, it's not happening, and the studies done on bolt carrier temps are showing that. They only get about 150 degress. Barrels go a lot higher.
Most of the gas entering the action comes from the chamber. A piston gun will have the exact same problem. I seriously doubt any measurable difference could be detected between DI and Piston in chamber deposits.
The action will get dirty anyway. If you've owned or cleaned a HK91, it's obvious.
The G-Series rifles are different again. The AR Platform with a gas piston does not have flutes in the chamber for hot gases to "cradle" or surround the brass to aid the extraction process (actually, obturation, I guess). So the will NOT have as much combustion residue with equal rounds fired.
not really, your snarky post shows that you lack a sense of humor, maybe you'd be more at home at poleupyourass.com.... I learn, trust me but I am a smart ass at heart and tend to try to lighten things up a bit. If you don't like that put me on ignore! If this is the type of forum that cant take a little humor now and then maybe Ill be better served just reading and not posting. But hey, thanks for chiming in and letting me know how intelligent you are!
I did learn a lot from this thread, but i find it funny how in so many different hobbies I have ventured in to over the years there always seems to be some type of debate going on, Ford vs chevy, 2 stroke vs 4 stroke, electric vs mechanical, brushed vs brushless.
the truth of the matter is that none seem better than the other just different and that seems the case here as well but often you get pin heads that dont want to see the other side of things and claim the one they own is king.
me, I am the type that will get both. Ill probably get a psd in 6.8 and then pick up a DI down the road a bit in 5.56.
Funny. You seem to think this thread is about "Ford vs. Chevy". Most posts prior to yours was extremely interesting, informative and I've learned a lot, as have others. People are putting up cogent arguments, and a lot of posters are just enlightening the rest of us on how each system functions, and what they do and do not do.
Last time I checked, the mission of www.M4carbine.net is not to "claim the one they own is king."
I think it is worth a slight thread hijack to point out that you do not understand what we attempt to do here. But even you have made a very good suggestion that I suggest you follow:
Maybe Ill be better served just reading and not posting."
Cool. See you when you have something constructive to say.
120 I don't know what your problem with me is, do you not like my name or pic of my dog, did your mom not hug you enuff, did your dad beat you to much? Either way I don't care, but I do think its pretty crappy for you to just post a personal insult to a new member questioning my intelligence simply because I made an analogy that it seems to be just a matter of opinion between the 2 systems. Nobody else seems to have taken offence to my "snarky" comment so I don't know why you would have. I certainly havnt made enuff posts here to piss you off yet so why the insults, do you treat all new members like this. Am I to understand you are the authority or the voice of majority on here? If so maybe I don't want to be here. Please if that's the case somebody other than 120 tell me to get lost!
The suggestion I made that was a good one must be you going to poleupyourass.com cuz its still there for some reason. Please no need to reply to me as I will not reply to you any more, I'm punishing you for 2 days, I will have you on ignore and will not see your posts!
To everyone else, sorry if I have offended anyone, if asked I will leave, if not I look forward to learning!!
120 I don't know what your problem with me is, do you not like my name or pic of my dog, did your mom not hug you enuff, did your dad beat you to much? Either way I don't care, but I do think its pretty crappy for you to just post a personal insult to a new member questioning my intelligence simply because I made an analogy that it seems to be just a matter of opinion between the 2 systems. Nobody else seems to have taken offence to my "snarky" comment so I don't know why you would have. I certainly havnt made enuff posts here to piss you off yet so why the insults, do you treat all new members like this. Am I to understand you are the authority or the voice of majority on here? If so maybe I don't want to be here. Please if that's the case somebody other than 120 tell me to get lost!
The suggestion I made that was a good one must be you going to poleupyourass.com cuz its still there for some reason. Please no need to reply to me as I will not reply to you any more, I'm punishing you for 2 days, I will have you on ignore and will not see your posts!
To everyone else, sorry if I have offended anyone, if asked I will leave, if not I look forward to learning!!
Fair enough! Now, please can we move forward? BTW, welcome to M4C.net!
You 2 kiss and make up.
The G-Series rifles are different again. The AR Platform with a gas piston does not have flutes in the chamber for hot gases to "cradle" or surround the brass to aid the extraction process (actually, obturation, I guess). So the will NOT have as much combustion residue with equal rounds fired.
The AR system with DI doesn't have flutes either. My point was that between DI and piston, you get the same amount of deposits in the chamber. They are about equally dirty.
A piston cannot eliminate that. The common assumption is that a piston gun will somehow be substantially cleaner, to the point it has an advantage over DI. The reality is that DI isn't that much dirty, both types of action usually suffer magazine and ammo faults to a much higher degree than action stoppages due to powder residue.
The mythology of DI would even purport that the amount of deposits on the bolt carrier is a major problem, when in fact, the bolt and upper have been designed with clearance to allow for that in combat. Many of the marketers of piston systems allude to dirty bolts and stoppages, but no one to this day can pin point the exact source of stoppage and say, it's between component X and Y.
That's because it doesn't exist, and the recent report by Mike Pannone suggests that after 2,500 rounds shot dry and left dirty, it's really not a problem. Lack of maintenance is. A piston gun shot dry and left dirty will also finally have malfunctions, too. Until its done, we won't know how many rounds, and how long.
It's really a moot point, clean your weapon daily in combat, and be advised you can't carry enough ammo to cause the problem. Fail to maintain the weapon, you ARE the problem. Just keep the upper track generously lubed, you can go 25,000 rounds and have other things literally wear out and break.
Nobody scraped the bolt tail on that loaner carbine. A piston gun, I would expect it would need it .
Failure2Stop
05-01-10, 21:30
Nobody scraped the bolt tail on that loaner carbine. A piston gun, I would expect it would need it .
I'm not following. Could you explain what you mean by the statement?
I'm not following. Could you explain what you mean by the statement?
Me too. I thought he had it nailed, until that statement. Is there something unique about piston guns that would cause some sort of buildup there?
BTW, Fords Rock, Chevies Suck! Derrr!
Magic_Salad0892
05-01-10, 21:53
Piston guns are cleaner, in my experience, or at least in the experience of people who own quality piston guns.
I'd show you pictures of my LWRCi at 1000 rounds without cleaning, and my KAC at the same mark, but I don't own a camera. :I
You can find pictures though of other people who have done the same.
I'm mainly talking about the bolt carrier area, not the bolt face.
In a piston gun the gas block is definitely a messy area.
Thomas M-4
05-01-10, 22:01
I'm mainly talking about the bolt carrier area, not the bolt face.
In a piston gun the gas block is definitely a messy area.
That is a none issue because the bolt carrier is made with plenty of clearance for carbon build up during normal operation.
Magic_Salad0892
05-01-10, 23:49
But would you agree that it's introducing unnecessary heat, and carbon build-up?
Piston guns and DI guns get just as hot on the BOLT FACE but on the bolt carrier it's a different story.
Also: I like having a one piece bolt carrier, than having a bolt carrier with gas rings screwed to it. It's an advantage in my opinion. Piece of mind.
But would you agree that it's introducing unnecessary heat, and carbon build-up?
Piston guns and DI guns get just as hot on the BOLT FACE but on the bolt carrier it's a different story.
Also: I like having a one piece bolt carrier, than having a bolt carrier with gas rings screwed to it. It's an advantage in my opinion. Piece of mind.
Considering that the bolt carrier sits in the middle of a large mass of aluminum, which is a very effective heat sink, heating up the bolt carrier will not be a big issue. The limiting factor will be the temperature of the barrel.
Magic_Salad0892
05-02-10, 03:35
That's a good point, but that gets into parts wear, and service life. Whereas I think that a piston system would be advantageous.
I'm not saying that the carrier can't take the heat, quite the opposite as we've seen. I'm saying that it can't be a bad thing for it to not be that hot. And it'll be good for service life I'm sure. My bolt carrier on my M6A3 is at almost 15 thousand rounds now. (6.8 - I've been doing a lot of shooting with the money I was going to put into a Mk. 18 Mod. 1 build. I'll get to it some other time...)
I'm just as confident in it as I was the day I got it, and don't see myself replacing it yet. I'll wait until I see significant parts wear. I don't think I would be that confident in the lifespan of a DI bolt carrier, though I've seen them go like 20 thousand rounds before replacement. (Steve from ADCO I think, has a Bushmaster bolt with 24k rounds on it that he's still using.) Just in case though I already have two spares and will probably order a third. A long with LWRCi's new Advanced Combat Bolt.
On a side note to the LWRCi ACB: It's pretty similar to KAC's E3 bolt. I like it a lot. I think FailZero is making them for LWRCi. I could be wrong though, and they'll work with DI guns as their not proprietary, so if any of you wanted the KAC bolt, but don't have a KAC gun, you can buy one and throw it in as soon as they become available. Which should be pretty soon. :) Just thought I'd throw that in there, seeing as I mentioned the ACB already.
ChicagoTex
05-02-10, 05:39
I'm not saying that the carrier can't take the heat, quite the opposite as we've seen.
Good logic.
I'm saying that it can't be a bad thing for it to not be that hot.
Good logic.
And it'll be good for service life I'm sure.
BAD logic. Since when does something being "not bad" mean it's "good" and therefore improves service life? Because you paid more for it? Reducing the heat a heat-treated steel bolt carrier and bolt are exposed to by 10, 50, or even 100 degrees on a regular basis will do NOTHING to improve service life by any measureable amount because the bolt and carrier will still be operating well within their 2000 degree or so temperature tolerance. If such trivial temperature differences made as big a difference as you seem to insist they do, we'd see SIGNIFICANTLY greater service life from weapons used in Artic climates.
I'm glad your LWRCi makes you FEEL more confident, but making up reasons for your feelings is doing nothing but digging you into a massive hole of faulty logic.
You bought a well-made piston rifle that works well for your purposes, but it's still not better than a comparable DI rifle no matter how much extra confidence you project onto it. That's just physics.
+1 on ChicagoTex
Unless you get the bolt carrier hot enough to change the lattice structure of the steel its not going to damge it. At that temperature the bigger issue would be damage to your aluminum receiver. If you really want to talk about heat issues you should first find your local engineering school and take calculus then thermodynamics followed by heat and mass transfer. Since you will already be there go ahead and take statics and dynamics so you can understand more about vectors so you can see what the resultant is from having masses move off the center line of the weapon.
Magic_Salad0892
05-02-10, 06:42
Good logic.
BAD logic. Since when does something being "not bad" mean it's "good" and therefore improves service life? Because you paid more for it? Reducing the heat a heat-treated steel bolt carrier and bolt are exposed to by 10, 50, or even 100 degrees on a regular basis will do NOTHING to improve service life by any measureable amount because the bolt and carrier will still be operating well within their 2000 degree or so temperature tolerance. If such trivial temperature differences made as big a difference as you seem to insist they do, we'd see SIGNIFICANTLY greater service life from weapons used in Arctic climates.
I'm not making up or directly insisting anything regarding bolt carrier temperature, because admittedly I'm not the most educated person on the subject matter. I'm only arguing what I know, and am not trying to come off arrogant, it seems that's what you projected my post as. I'm sorry if that's what it seemed like.
I'm not arguing that pistons are better than DI guns. I'm arguing that they are both equal for different reasons.
I admittedly don't KNOW if it'll increase service life, it's just something I think is worth arguing.
Here's something I noticed, I'd like you to weigh in, because I don't know the cause.
In my piston gun why doesn't my trigger group have carbon build up? My KAC does. LWRCi has none to speak of. I don't know why, but I do like that.
Here's another advantage to some piston designs - - The ability to completely turn your gas system off, or adjust it according to if the gun is suppressed, or neglected.
Though, I'm sceptical to how much this would matter to a DI gun.
Do you think there is an advantage of having a piston in a full auto, suppressed, or short barrelled rifle? Being more educated on heat properties I'd like to know your opinion.
Being a shooter of suppressed SBRs I much prefer the piston operating system.
I can't give a scientific reason, because admittedly I am biased. It's a personal preference. I do like that it's a little more pleasant to clean because the carbon isn't caked on to the carrier. This may or may not be a product of the Nickel Teflon coating of the LWRCi rifle though,
ChicagoTex
05-02-10, 07:51
The trigger group on your KAC develops carbon build up because of the DI gasses and unburnt carbon being shoved into your action from the DI system. You are correct in that piston systems won't yield anywhere near as much (if any) carbon build up in that area.
But the carbon buildup doesn't threaten reliable function of the rifle without an insane amount of neglect, the kind that'd stop a rifle for all kinds of reasons, whether DI or Piston (unless for some bizarre reason you made it a point to regularly clean everything on your DI rifle but your trigger group...)
The reason pistons generally work better on supressed SBRs really has nothing to do with heat, and everything to do with the fact that a piston system can regulate itself in terms of force applied to the bolt carrier. The AR's DI gas system was never designed or intended for short barrel platforms and once you start getting under about 12" or so the gas port needs to be enlarged to compensate. You basically have to overgas the system to get it to run on a carbine-length gas tube because the dwell time is too short. This results in a great deal of extra violence to the bolt, carrier, and spring causing early breakage and reducing reliability (adding a supressor further increases pressure by creating artificial dwell time for gasses in the barrel). In contrast, a piston system will use as much gas is necessary to unlock the bolt and bleed off the excess, ensuring that you use only just enough gas no matter what round you're shooting and whether or not you're shooting supressed.
What I'm basically saying is, in order to get an SBR to run AT ALL, you've got to push the tolerances of the BCG, springs and buffer, and then when you add a supressor that pushes it past tolerance in FORCE, not temperature.
Note however that you could build an SBR that would only run reliably supressed and not go past tolerances, but then if you ever remove the can, you're SOL.
In short: the shorter the rifle, the bigger difference little changes make, pistons can autocorrect for little changes on the fly where DI's can't, but this really doesn't become an issue until you start getting down into barrel lengths of seriously questionable usefulness.
The AR's DI gas system was never designed or intended for short barrel platforms and once you start getting under about 12" or so the gas port needs to be enlarged to compensate. You basically have to overgas the system to get it to run on a carbine-length gas tube because the dwell time is too short. This results in a great deal of extra violence to the bolt, carrier, and spring causing early breakage and reducing reliability (adding a supressor further increases pressure by creating artificial dwell time for gasses in the barrel).
What I'm basically saying is, in order to get an SBR to run AT ALL, you've got to push the tolerances of the BCG, springs and buffer, and then when you add a supressor that pushes it past tolerance in FORCE, not temperature.
with that being said are there any companies out there that make a dependable sbr di system or is piston really the only choice for sbr?
Thomas M-4
05-02-10, 09:12
But would you agree that it's introducing unnecessary heat, and carbon build-up?
Piston guns and DI guns get just as hot on the BOLT FACE but on the bolt carrier it's a different story.
Also: I like having a one piece bolt carrier, than having a bolt carrier with gas rings screwed to it. It's an advantage in my opinion. Piece of mind.
The BC heat is a none issue. Have you seen the COLT M-4 self destruction video. With a government profile barrel they continuously do mag dump after mag dump on FA. Until the 4150 cmv barrel droops :eek: the barrel get so hot the steel turns soft and the barrel will physically droops until a round goes though the side of the barrel. When it comes to heat the BCG is not taking the abuse that the barrel is going through. In other words the barrel will fail from heat before the operating system.
ChicagoTex
05-02-10, 09:36
with that being said are there any companies out there that make a dependable sbr di system or is piston really the only choice for sbr?
There are absolutely dependable DI SBRs. The problem is you have to tune them either for supressed use or non supressed use.
a DI <12" SBR tuned for non-supressed use will be severely beat up if a supressor is added. You could shoot a few rounds supressed here and there, but not a regular diet without hefty damage.
a DI <12" SBR tuned for supressed use will be less beat up than the one configured for non-supressed use when using a supressor, but may not function reliably when the supressor is removed (some hotter ammo MIGHT cycle okay, but it'll definetely be picky).
In order to perform both duties equally well, you'd either need a piston setup or an adjustable gas block. While the adjustable gas block will work, it'll be more difficult and time consuming to adjust properly and will still ultimately be less flexible than the piston design.
well, once i decide to go suppressed I wont turn back, my intention is to have an sbr 8-10 suppressed for HD but have a 16" for target fun. just havnt completely decided on what brands are the best quality and dont seem to have a clear preference on di or piston yet.
ChicagoTex
05-02-10, 09:53
well, once i decide to go suppressed I wont turn back, my intention is to have an sbr 8-10 suppressed for HD but have a 16" for target fun. just havnt completely decided on what brands are the best quality and dont seem to have a clear preference on di or piston yet.
I'd advise you to look very carefully at the ballistics for .223/5.56 with barrels that short. Below 12" you're better off with a 9mm +P HANDGUN.
ETA as for brands: Noveske, Colt, BCM, Daniel's Defense, and Spikes Tactical are the top players for DI guns. Pistons I'd favor POF, though LWRCi and LMT are worth considering. If you do go the piston route just for the love of god don't buy a Ruger.
I'd advise you to look very carefully at the ballistics for .223/5.56 with barrels that short. Below 12" you're better off with a 9mm +P HANDGUN.
ETA as for brands: Noveske, Colt, BCM, Daniel's Defense, and Spikes Tactical are the top players for DI guns. Pistons I'd favor POF, though LWRCi and LMT are worth considering. If you do go the piston route just for the love of god don't buy a Ruger.
i do have a 9 pistol as well, the one i was looking at specifically was the lwrc psd in 6.8. but im a newb just getting my feet wet, doing a lot of reading before parting with my $$$
ChicagoTex
05-02-10, 10:06
the one i was looking at specifically was the lwrc psd in 6.8
Unfortunately I know close to nothing about the 6.8 (except that, given the cheapest I've ever seen was 90 cents a round, it's definetely not for me unless and until I start handloading). My advice would be to do a search on 6.8 SBR ballistics and if that turns up nothing, start a new thread and let the 6.8 fans/experts tell you all about it.
Failure2Stop
05-02-10, 15:51
We are getting way off topic.
For information on 6.8, refer to the "Beyond 5.56" sub-forum.
Magic_Salad0892
05-02-10, 18:51
I'd favor the LWRCi over the still awesome POF any day of the year.
Better coatings, looks better, much better CS, you get the advanced combat bolt, etc.
LWRCi is the KAC of piston guns. :)
Y'know. I'd like to thank everybody in this topic for being informative and cordial with me in our debate. It's nice to see such a debate not turn into an argument.
I also appreciate that my questions were answered without bullshit, and that nobody hates me just because I like having a metal rod over my barrel.
And yeah, there are really good DI SBR options, talk to Grant about that he works with them. I run a KAC in that department. (I WANT A PDW.)
http://vuurwapenblog.com/2010/05/06/
Standard disclaimer: I'm not a scientist and this was not a scientific test. Any conjecture on my part is purely an uneducated guess.
As I've written before, POF-USA provided me with two of their upper receivers - one is of their standard P-415 design and the other is actually operated via a standard gas tube. It's called the RDIK.
This gave me the opportunity to compare how each handled heat. That is, just how effective are all the design changes POF has made to the AR receiver, barrel nut, and handguard? Well, as I found out, they're quite effective. However, that test was pretty limited - only 30 rounds per weapon - and I wanted to step it up a little.
Today I put 80 rounds through each of three ARs - the P-415, the POF RDIK, and an M4 type AR with double heat shield handguards - and will shoot more in the next few days with other weapons. I also took chamber and bolt face temperature readings, in addition to the handguard temp (average of 4 places on the handguards) and gas block/barrel temp.
The rounds were fired as quickly as possible, and the rifles were left with the bolt carrier group in the forward and locked position. Temperature readings were taken immediately after firing and at two minute intervals thereafter, out to 12 minutes post fire.
We'll start with handguard temperature.
http://www.545ar.com/80rdHG.jpg
As you can see, the M4's double heat shield handguards were much hotter than either POF offering. The POF RDIK, in fact, had a slightly cooler handguard than the POF P-415.
This was in part due to the very hot gas block of the P-415. Here are those temperatures:
http://www.545ar.com/80rdGB.jpg
It wasn't quite as scorching as the M4's 353 degrees immediately after shooting, but it was over 320. The POF RDIK was drastically cooler - it never exceeded 200 degrees.
Chamber temperatures were much closer for all weapons.
http://www.545ar.com/80rdCH.jpg
The P-415 did stay cooler than the RDIK, with a difference of roughly 10 degrees. The M4 was hotter than either of the POF weapons, due in no small part to the heat sink barrel nut used on the POF rifles.
The following graph shows bolt face temperature.
http://www.545ar.com/80rdB.jpg
It would appear that a large portion of the heat reaching the standard AR-15's bolt comes from the front - that is, the chamber. If we compare chamber and bolt temperatures, the RDIK and M4 hardly ever had more than a 2 degree difference between the chamber and the bolt (with the bolt normally being 1-2 degrees cooler than the chamber). The P-415 bolt, on the other hand, generally stayed about 10 degrees cooler than the chamber.
http://www.545ar.com/80rdCHB.jpg
What does this all mean? Well, to me, it means that getting the heat out (circulating air) is more important than trying to keep the handguards cooler (insulating the barrel with double heat shields) - regardless of the operating system you choose. It would appear that the piston/op-rod P-415 does slightly bolt face temperature - but the RDIK does a very fine job of keeping the chamber area cool in its own right, which in turn keeps the bolt cooler.
It seems that there is no free lunch, and the heat which is not present in the P-415 chamber and bolt is very present at the gas block. The heat sink features and wide open handguard with lots of cooling slots almost seem necessary to keep the barrel/gas block temperature relatively in line with that of the M4 type AR. I would really like to test an op-rod conversion that does not have the heat sink barrel nut, big handguard, etc.
I would assume, based on these graphs and the comparison of the three uppers, that the large majority of the temperature of an AR-15 bolt during sustained fire can be attributed to the "fire in the barrel", and a minority comes from the gas which circulates through the action. In other words, with the piston/op-rod system, the chamber "heats" the bolt, whereas in the standard operating system, the bolt is heated not only by the chamber but in a small way by the gas coming through the gas key, which in turn causes the bolt to pass some heat back to the chamber. As a result, the temperature of the bolt and chamber on a standard AR are married to one another to a greater degree (ha, ha) than on the P-415.
Again, I'm not a scientist. If anyone has a better conclusion based on the above data, I'm all ears.
Cincinnatus
05-07-10, 01:52
http://www.armalite.com/images/Tech%20Notes/Tech%20Note%2048,%20Barrel%20Design,%20Heat,%20and%20Reliability,%20030824%E2%80%A6.pdf
Here's some great info on heat and weapon's failures that Sinister posted on another thread.
The reality is that DI isn't that much dirty, both types of action usually suffer magazine and ammo faults to a much higher degree than action stoppages due to powder residue.
That's because it doesn't exist, and the recent report by Mike Pannone suggests that after 2,500 rounds shot dry and left dirty, it's really not a problem. Lack of maintenance is.
LINK: http://www.defensereview.com/the-big...m4-unreliable/
The Big M4 Myth: “Fouling caused by the direct impingement gas system makes the M4 Carbine unreliable.”
On March 19, 2010, in Featured, Rifles And Carbines, Special Operations, by David Crane
By Mike Pannone
Info@CTT-Solutions.com
All photos contained in this article were taken by Mike Pannone for DefenseReview.com, and are copyrighted. Mike Pannone and DefenseReview.com own the copyright on these photos.
March 19, 2010
Here’s my question for those that subscribe to the direct impingement fouling concept:
I fired 2400 rounds of M193 through a 14.5” M4-type upper receiver from Bravo Company Manufacturing (BCM) with no lubrication, and without any rifle-caused malfunctions. So; why can I get my direct impingement rifles to repeatedly do things that conventional wisdom says they can’t do?
This article is not a direct impingement vs. piston driven operating system debate and does not discuss piston guns at all. It is specifically dealing with a 14.5”AR-15 upper receiver with .062” gas port that’s as close to a Mil-Spec M4 upper as I could find on the civilian market.
All I have ever asked and required of myself (and others) as a professional is that everything I say or write must be capable of being substantiated. I am asking some questions and giving my opinions, observations, and conclusions based on my own experience and testing.
For years I have been told, and heard others repeat, incessantly, that the direct-gas-impingement M16/M4 family of weapons is flawed because they deposit gas and powder residue in the upper receiver, and thereby are inherently unreliable with hard use. That sounds good in theory. However, in practice, I have not seen nor experienced it with my guns as a special operations soldier or civilian instructor. Why is that? Why don’t I have said commonly referred-to fouling problem with even excessive use and minimum maintenance?
When I returned from Iraq in 2005, I was a primary instructor on a rifle course with the Asymmetric Warfare Group (AWG). During that time as I have mentioned in previous articles I began a quest to find out what made the M4/M4A1 Carbine run well, and what stopped it from doing so. In that time I spent a year at the 82nd Airborne Division training with infantry units prior to their deployment on the Iraq surge. During this time, I saw every manner of malfunction and never saw a rifle that was not well cared for (the soldiers attending were more senior and specially selected, as well as being members of the highly disciplined 82nd Airborne division). Each time there was a malfunction, if possible, I would run over and observe what had happened, then write it down in my log book. What I eventually realized was that when magazine issues were removed, along with broken parts, about 80% of the malfunctions had been accounted for. The rest were failures to properly extract and eject, and failures to go into battery. That is where I realized my rifles were superior to the ones issued. The only problems I had experienced with my own guns were double feeds which are exclusively magazine caused.
What’s odd is that I was using a civilian version of an M4 that was nearly identical to the ones used by the paratroopers of the 82nd. My rifle utilized a DPMS chrome-lined 16” M4-profile barrel with a Larue free-float forend rail tube. After that barrel was shot out I went to a Noveske 14.5” Afghan barrel, and then finally to a Noveske 14.5” N4 cold hammer forged, double-chrome-lined barrel. Aside from being semi-auto-only instead of select-fire (i.e. burst-fire or full-auto capable), and one having a barrel that was 16.1” vs. 14.5”, they were functionally the same rifle. The difference was that I used a heavier Sprinco buffer spring (correctly called an action spring), a DPMS Extra-heavy buffer (.2oz lighter than a Colt H3 buffer), and a 5 coil extractor spring with a Crane O-ring for added extractor tension. Those drop-in parts made my rifles obscenely reliable, and still do. The spring-and-buffer combo I use works in mil-spec-size gas port rifles (.062” as per NAVSEA Crane a.k.a. Naval Surface Warfare Center, Crane Division) with 14.5” or 16” barrels and a 7.5” carbine gas system. There are some rifles on the market that have smaller gas ports than the Colt M4 in its military configuration, so the spring and weight may not work in them, as they may cause short cycling issues. I had the luxury of shooting my rifle without maintenance in a training environment until it failed. I routinely went well over 2500 rounds with only a few drops of oil and a bore snake run through the barrel every morning. I was convinced there and then that fouling was not nearly the issue it was purported to be, and that the real issue was weak springs and a buffer that was too light.
My Test:
Recently, I received a milspec equivalent (barrel length/gas port size/gas system length) M4-type upper from Bravo Company USA (BCM) to test my theory that a heavier buffer and spring with enhanced extractor tension would give extraordinary reliability with no lubrication or maintenance whatsoever. I have shot over 2500 rounds with the FailZero kit with EXO Technology coating on four separate occasions with no lubricant, as well as a ceramic coated rifle (to include bolt and bolt carrier group) from Next Generation Arms that currently has 4000 rounds on it without cleaning or lubricant, and also no malfunctions. I have also routinely shot a Noveske N4 14.5”-barreled rifle over 2500 rds with only 6-8 drops of oil every 500-700rds fired without any issues. If I used those rifles or parts for my test, many would say “well those are custom coatings/guns and military guns don’t have that.” For that reason, BCM was kind enough to send me a stock 14.5” upper on which to do the test. Prior to the test I did the following:
1. Remove all visible oil and lubricant from the inside of the upper receiver.
2. Disassemble the bolt carrier group (BCG) and remove all lubricant inside and out
3. Put a Crane O-ring on the existing extractor spring
4. Use a lower receiver with a Sprinco standard Blue spring and an H-3 buffer (I used an H3 because it was close to the DPMS Extra-heavy buffer I use in most of my rifles.
(*Writers note: A standard rifle buffer is 5.2oz. For a Carbine receiver extension a standard H buffer is 3.8oz, H2 is 4.7oz and H3 is 5.6oz.)
After I had done that, I fired 2400 rounds of M193 through it in six sessions, often shooting it so hot that I could not hold the forend without gloves. The first of such sessions was in the presence of two Border Patrol BORTAC snipers, and it consisted of 330 rounds in 25 minutes. This included zeroing the optic so the bulk of the rounds were fired in a 20 minute period by all three of us. (Note: At the conclusion of this, I pulled the bolt carrier group out and held it by the lugs with my bare fingers. That’s another myth (to debunk) for another article. I did this a second time later during the test where I had shot the rifle so hot I needed gloves to hold the forend, then shot 120 rds in 2:35 and again held the bolt by the lugs with bare fingers.) The rifle had no issues other than some test magazines that did not feed the last round properly. Once those test magazines were removed, the rifle always locked to the rear on the last round fired and did not feel sluggish.
With good magazines–I used USGI aluminum of various makes so as to replicate military use as closely as possible–there were no issues until I reached 2450 rounds fired. At 2450 rounds the rifle would not complete the recoil cycle due to the additional friction caused by the fouling and no lubrication, and exacerbated by the extra buffer weight. Once the rifle began short cycling, it did so every shot. In diving medicine, that’s called “dramatic onset of a symptom”. It was as though a switch had been flipped and the rifle just stopped working.
Rounds fired per session were: 330, 510, 540, 450, 450, 120* (Note: Failure point was end of 6th magazine/2440rds. Problem: chronic short cycling due to excessive fouling caused friction.)
At the failure point I replaced the H3 buffer with an H buffer, and the rifle ran reliably again. I finished the remaining rounds in the 6th magazine of the session, and continued shooting. At 2500 rounds, the rifle ran, although quite sluggish in counter recoil. Then, nearly on cue, the rifle stopped again, this time at the 2540 round mark, and the last ten rounds were accomplished by tap-rack (performing a tap-rack-bang drill) each time. Just to isolate the issue I put the BCG in another dirty but oiled upper of same design and it ran easily (with H3 buffer reinstalled). I returned the BCG to the original upper, oiled it, and the rifle immediately came back to life firing another 90 rounds smoothly and without issue (2630 total rounds fired for test + 30 in replacement receiver cited above).
Here are the findings of my testing:
· When the rifles become fouled, they have more drag (friction) inside the upper receiver, which slows down the bolt carrier group. This along with the pressure on the bottom of the bolt carrier from a loaded magazine will slow the BCG down enough to keep it from reliably going into battery during the counter-recoil cycle. The heavier buffer and spring completely remedy this, but there is a crossover point. That crossover point on a bone-dry stock M4/M4A1-type AR carbine upper is about 2400rounds fired. At that point, if there is enough buffer spring tension to drive the BCG into battery, then it cannot fully cycle. And, if the spring is light enough to allow the weapon to fully cycle to the rear, it does not have enough force to go fully into battery. The changing from an H to an H3 buffer only gave an additional 80 rounds of reliability. And, given the parameters of the test (no lube) and the dramatic increase in shootability using a heavier buffer, I am still a proponent of a buffer heavier than an H.
· With the Sprinco enhanced Blue action spring (or comparable extra-power spring) and an H2 orH3 buffer, unless there is a rigid obstruction present in the barrel extension, the rifle will reliably go into battery. Note: I routinely take “damaged” or discarded rounds (see first article on M4 reliability) that have been lying around or have deformed cases from the malfunctions block I conduct and load them into my magazines. I will shoot them all without issue, unless they are catastrophically disfigured or the projectile is pushed back into the case (creating a safety issue due to increased chamber pressure). The heavier buffer and added spring tension effectively resizes the case and fires it.
· A benefit of the additional spring/buffer weight is that it slows down the unlocking and extracting tempo, increasing the locked chamber dwell time and allowing for much more reliable extraction and ejection. This is because the longer dwell time allows the chamber pressure to recede more, as well as transferring heat from the case to the chamber walls. It also offers a softer-shooting rifle because the recoil impulse is transmitted over a longer period of time, hence lower ft-lbs/second received at the shoulder.
· With an enhanced extractor spring (BCM 4 coil, Sprinco 5 coil or comparable) and a Crane O-ring, I have not experienced any failures to extract except for faulty ammunition (specifically Radway Green training ammunition used by the 82nd in 2006) The SOPMOD bolt upgrade kit (new extractor and pin, 5 coil extractor spring, Crane O-ring and new gas rings), first fielded by SOCOM, should be standard on all M4’s used by the military or law enforcement.
*I have heard of some rifles that will not function properly with both an enhanced extractor spring and a crane O-ring installed. The symptom is the extractor does not release the brass from the bolt face causing a failure to eject. I have never experienced this with my personal rifles, but am currently working with Lou Patrick of on finding the reason for this. Lou is one of the most overall knowledgeable gunsmiths I have ever met, and is also a former gunsmith for the Army Marksmanship Unit (AMU).
**Test-fire any enhancements before fielding.
Conclusion:
Fouling in the M4 is not the problem. The problem is weak springs (buffer and extractor), as well as light buffer weights (H vs. H2 or H3). With the abovementioned drop-in parts, the M4 is as reliable as any weapon I have ever fired, and I have fired probably every military-issue assault rifle fielded worldwide in the last 60 years as a Special Forces Weapons Sergeant (18B). An additional benefit of the heavier spring/weight combo is that it transmits the energy impulse of the firing cycle to the shoulder over a longer duration, lowering the amount of foot pounds per second and dramatically reducing the perceived recoil. Follow-on shots are easier to make effectively, and much faster, especially at 50 meters and beyond.
I reliably fired 2400 rounds (80 magazines) on a bone dry gun, and I would bet that is a lot more than any soldier or other armed professional will ever come close to firing without any lubrication whatsoever. So, disregard the fouling myth and install a better buffer spring, H2 buffer, enhanced extractor spring and a Crane O-ring (all end user drop-in parts). With normal (read “not excessive”) lubrication and maintenance, properly-built AR-15/M4 type rifles with carbine gas systems will astound you with their reliability and shootability.
About the Author: Michael Pannone a.k.a Mike Pannone is currently the owner/operator of, and senior instructor for, CTT Solutions, which is a tactical training (including tactical shooting) and consulting firm. He’s also a certified Colt Armorer. Mr. Pannone is a former operational member of U.S. Marine Force Reconnaissance, U.S. Army Special Forces, and specially selected elements of the Joint Special Operations Command. He has participated in stabilization, combat, and high risk protection operations in support of U.S. policies throughout the word as both an active duty military member, and a civilian contractor. During his military career, Mr. Pannone was the Distinguished Honor Graduate of a Level 1 SOTIC held at Ft Bragg. He currently instructs U.S. military, law enforcement (LE), and private citizens around the country as an adjunct instructor with several different organizations. He can be contacted via e-mail at Info@CTT-Solutions.com.
variablebinary
05-09-10, 17:41
I like pistons for SBR's and suppressed weapons but otherwise, DI is fine.
Yeah they are a little more of a pain to clean even with low round counts, but I challenge anyone to say they are getting quantifiable performance and reliability improvements from a 16" piston over a 16" DI gun.
Magic_Salad0892
05-10-10, 04:30
That was probably the most informative article about DI reliability I've ever read. :)
I shall now make some modifications to my already near-perfect 11.5'' KAC.
And my 12.7'' LWRCi uppers. :)
Thanks for that.
Thomas M-4
05-18-10, 10:19
Propellant adds very little to heat build up. Friction is the main cause of heat, period.
How is that ?
Have you ever seen a m224 mortar tube it has cooling fins no friction on the mortar round it uses a zero friction gas check. Propellant adds very little heat :rolleyes: I guess we could all swap to sabot rounds and never have a heating problem again.:rolleyes:
http://www.fas.org/man/dod-101/sys/land/m-224-dvic503.jpg
It's really a moot point, clean your weapon..., and be advised you can't carry enough ammo to cause the problem. Fail to maintain the weapon, you ARE the problem.
I agree. This is the same thing I tell persons who deride the 1911 pistol platform.
Both work very well, but why add apiston to a AR when you can just buy a galil? THe galil is bascally a compromise between the Ar and Ak Platform. Not as accurate as an AR, not as reliable as an AK, but somewhere in between. I'm not the biggest fan of the Galil as it is heavy as hell and very expensive for what you're getting. Shot one once and it was fairly accurate, but tooo darn heavy and not balanced well.
If you like DI; buy one.
If you like Piston; buy one.
I very much doubt anyone will shoot enough ammo to see either system have a catastrophic failure. I tried to shoot my DD M4 so dirty it would fail, but I didn't have enough funds to do so. After thousands of rounds and nothing but bang, bang, bang; I decided anyone who thinks a DI system has problems, isn't doing any research, just repeating words they saw or heard somewhere. So why "fix" a problem that just doesn't exist? I have no answer for that one. If you prefer the piston system great, but the DI system is not flawed; it delivers as it is supposed to.
Seriously has anyone ever shot enough ammo to dirty up a DI gun to the point of failure? (Only real world failures I know of are due to mag, ammo, and the occassional part breakage/failure, I've never heard of a DI gun failing due to carbon build up; getting real sticky and finicky yes; but that is what a frorward assist and drips of lube is for.
Has anyone ever shot up a piston system so dirty it failed?
I would really like to hear about either scenario if so...
I guess the final word here from me would be:
Is it worth twice the amount of $$$ to buy a piston system in an AR/M16/M4 style platform...
No. I cannot find any justification, other than persoanl preference dicatating one liking the system better than another; and if you like it better, go ahead and use it.
By the way the DI system was specifically meant to run dirtier than hell with lots of lube.
Solutions to problems that just don't exist in reality...
Just to stir the pot a little...
http://img.photobucket.com/albums/v342/stephen_101st/Gear/dust.jpg
Just to stir the pot a little...
http://img.photobucket.com/albums/v342/stephen_101st/Gear/dust.jpg
Only 882 stoppages in 60K rounds with exteme dust exposure? That's what......1.5% failure rate? Sounds pretty good to me considering I won't be subjecting my DIs to exteme dust testing. If it runs in exteme conditions 98.5% of the time, what more could I hope for?
Only 882 stoppages in 60K rounds with exteme dust exposure? That's what......1.5% failure rate? Sounds pretty good to me considering I won't be subjecting my DIs to exteme dust testing. If it runs in exteme conditions 98.5% of the time, what more could I hope for?
Something better? Why wouldn't you want the added reliability?
Stephen
Thomas M-4
06-22-10, 16:26
Hmm XM8 and Scar both gas tappet operating system.
ForTehNguyen
06-22-10, 16:58
I wouldnt want every 15 stoppages every 1000 rounds, but on the other hand Filthy 14 went 1000s upon 1000s of rounds without a problem.
ChicagoTex
06-22-10, 17:08
I tried to shoot my DD M4 so dirty it would fail, but I didn't have enough funds to do so. After thousands of rounds and nothing but bang, bang, bang; I decided anyone who thinks a DI system has problems, isn't doing any research, just repeating words they saw or heard somewhere.
Generally yes, but remember also that when a Fudd's DPMS or Oly chokes on Wolf .223, they will often see it as a an anecdote against US Military Colts running 5.56 (after all, they're both "mil-spec" and .223 and 5.56 are really "the same round").
Hell, that's how AKs got such a bad rep for accuracy ("my WASR shoots 6MOA, therefore the AK as it is issued everywhere, must be a 6MOA gun")
Belmont31R
06-22-10, 17:14
Something better? Why wouldn't you want the added reliability?
Stephen
For the military those guns might be an option but at present they have a lack of modularity, parts replacement, cost factor, etc.
In two deployments, and six years I never saw a weapon go down due to dust alone. Most people were trying to shoot them dry, and bad mags. Im not doubting there are more reliable systems out there but at the same time I don't think "real world" conditions are so bad the AR platform is unreliable. The only time I had one jam up on me was in basic after low crawling a good distance through sand. There was so much shit in the action I doubt any gun would have been functional. Aside from that Ive shot them in blowing sand and dust storms numerous times, field ops, missions to where the gun was coated in a sticky dirty concoction (those who've patrolled in Iraqi cities prob know what Im talking about), and never had one fail. Here its windy all the time, and everytime I go shooting the guns get covered in crap.
...By the way the DI system was specifically meant to run dirtier than hell with lots of lube...I don't know about the lube, but Eugene Stoner designed the rifle to run clean. It was designed to use a stick powder that left behind little to no residue and was touted as being self-cleaning. The gasses entering the action were to blow residue & dirt out.
McNamara & his "Whiz Kids" decided to change the powder specification to a Winchester ball which uses a graphite coating to control burn rate. The powder was known for leaving a sticky residue. (That's why I've never used powders like Winchester 741.) They did it without testing and issued the rifles without cleaning kits, still touting the M16s "self cleaning" design
crusader377
06-22-10, 21:52
Just to stir the pot a little...
http://img.photobucket.com/albums/v342/stephen_101st/Gear/dust.jpg
I have seen this chart several times before and although the SCAR/XM8/HK416 may be a more reliable system there are a few points and questions worth noting.
First, the XM8 never made it in production and the SCAR and HK416 are limited production and at the time of this test were semi-custom rifles. In contrast, Colt manufactures thousands of M4 a week. I wonder if the XM8, SCAR, HK416 would have performed as well if they were truly production rifles.
Second, were they using the same service issue magazines as the M4 or were they using improved or propriety designs?
Third, did all of the rifles receive the right maintenance to allow them to run at maximum effectiveness? For example, it is well known the piston rifles require less lube than the M4 DI system. Was the M4 lubed like the competitors or was it well lubed to allow for maximum reliability.
Fourth, I wonder how an improved M4 using some of the more recent advances in the platform would perform? I was thinking of something like a KAC SR15.
pleaforwar
06-23-10, 01:16
Just to stir the pot a little...
http://img.photobucket.com/albums/v342/stephen_101st/Gear/dust.jpg
I was under the assumption that the second round of testing proved much more favorable numbers for the M4. :confused:
AllAmerican
06-23-10, 09:08
in a DI system the gasses are bled off into the gas tube. Heat is carried with these gasses away from the barrel and vented into the action to be absorbed by the parts and the surrounding air.
Not wrong, the common belief that the gasses are released into the action by the gas tube, not so much.
The gas is delivered to the bolt carrier and vented out the two holes in it that face the ejection port. The bolt unlocks, and about the same time the key clears the gas tube, the brass is being retracted out the chamber.
Gas being metered through a .063 hole in the barrel is going to be a much smaller volume than the gas being exhausted past the brass into the chamber and action. All gas action semi's do this, the maintenance manuals are very specific about cleaning residue out of the chamber.
I don't have a non contact thermometer, but I suspect that semi auto brass stays hotter than bolt action. Two reasons, it's bathed in gas as it's extracted, and it doesn't get to transfer it to the chamber as the dwell time is pretty short. A bolt action can hold it's brass for a long as the operator wants.
It's a common misconception that the gas tube dumps a lot of gas into the action, it's not happening, and the studies done on bolt carrier temps are showing that. They only get about 150 degress. Barrels go a lot higher.
Most of the gas entering the action comes from the chamber. A piston gun will have the exact same problem. I seriously doubt any measurable difference could be detected between DI and Piston in chamber deposits.
The action will get dirty anyway. If you've owned or cleaned a HK91, it's obvious.
Isn't the first round fired cooler than say the 30th round out? I would be interested in the temperature difference between the 1st and last round from say a 30 round mag, (talking about the brass case here) and then maybe a 2nd and then 3rd mag checking 1st and last round temp... would that give an idea of how fast the system is heating up?? I don't have the thermometer, but I would be interested in that.
This is a good thread! I only have experience with the DI system so I can't comment on the other. But have never had any problems with it, that includes military and LEO use of it. Since 1972.
Thanks for the information!
I don't know about the lube, but Eugene Stoner designed the rifle to run clean. It was designed to use a stick powder that left behind little to no residue and was touted as being self-cleaning. The gasses entering the action were to blow residue & dirt out.
McNamara & his "Whiz Kids" decided to change the powder specification to a Winchester ball which uses a graphite coating to control burn rate. The powder was known for leaving a sticky residue. (That's why I've never used powders like Winchester 741.) They did it without testing and issued the rifles without cleaning kits, still touting the M16s "self cleaning" design
My wording was poorly chosen here...
I should have said that the M4 carbine platform has been built up over the years to run dirty as hell with generous; but not excessive lube (Ask any soldier, they will tell you it will run dirtier than hell, but without lube the suckers fail every time). I am aware of the Stoner/McNamara/vietnam debaucle ; it is one prime example of how politicians know absolutely dick, and screw everything up.
About the graph posted with the failure rates per 60,000 rounds; where is that taken from? Can we see the entire test findings including the test parameters?
I don't doubt that piston systems are more reliable over a huge amount of rounds/the rifles life cycle; however as I stated before; I tried pretty hard and spent a good deal of money trying to get my rifle to fail from being dirty. It just wouldn't happen, and if I can shoot all the ammo I can afford and still need to shoot more to get a malfunction; well I guess I am in trouble way before the gun will fail; so I should use the money I would have spent on a piston system to buy more ammo...
I don't deny the viability of the piston system; just that it is; in my humble opinion; unecessary for any type of application I could possibly find use for. So why spend 2X, and sometimes more money, when you could just buy ammo, tac lights, scopes, holo's, sling, extra mags; shit possibly even another rifle etc...
Shit, if my rifle would have had a malfunction I could attribute to being dirty during my testing; that would have been the "ammunition" to take to the wife to justify the $$$ price tag of a piston system; but it just didn't happen, so there is no justification from where I stand. Believe me I like new toys, but they have to have a significant amount reasoning/real world application behind them for me to want to buy/play with them.
It seems to me buying a piston system for an inflated price over a DI system, is tantamount to buying a monster truck to haul an ATV; yeah it can haul the ATV real well, but so can a ford F-150 for half the price and virtually the same outcome; plus you have extra $$$ cash to spend on upgrades to the F-150.
I would love to get the other info/parameters of that test you referenced in your stoppages per 60,000shot table...
About the graph posted with the failure rates per 60,000 rounds; where is that taken from? Can we see the entire test findings including the test parameters?
Here is a link to an Army Times article on the test. I can't find the full report, but I know I've got it saved somewhere.
http://www.armytimes.com/news/2007/12/army_carbine_dusttest_071217/
Stephen
Stephen,
Thanks for the link; interesting test.
I have to say that the difference between test #1 and test #2 leaves much to be desired. The control aspect was the same, yet the M4 had less than 1/2 of the failures between tests? That sounds way off to me? Plus the (307) failures for the M4 from one test are just about in line with the piston systems rate of stoppages.
Also there is no way of knowing the set control parameters for this test. As they did not list them; not very well at least.
EG:
Did they use new colt M4's or used ones? Were the weapons broken in prior to testing? Did they use GI or Aftermarket mags (as others have questioned)? Did they use a "control" amount of lube evry time they lubed, or just dap some on differently each time?
That test leaves very much to be desired on my end...
If you are able to locate the full report I would be very interested to read it.
Thanks again.
The main point I'm trying to get across is that the current issue M4 is 50 year old weapon, material, and manufacturing technology. To say that the M4 is perfect as is is very dogmatic and unrealistic. It is a fine weapon; I carried one for 4 years (with 5 years of M16A2/A4 before that) including a year downrange during OIF1, but there is lots of room for improvement just to bring it up to modern standards. If the military were to ride out the M4 for another 10 years they should at least consider things like hammer forged barrels, Salt-Bath nitride for steel components, nickel teflon coatings for operating components, improved material selection for bolt/extractor, etc. I'd like to see a piston operating system as well, but I'll try and stay out of that arguement here...
Stephen
The main point I'm trying to get across is that the current issue M4 is 50 year old weapon, material, and manufacturing technology. To say that the M4 is perfect as is is very dogmatic and unrealistic. It is a fine weapon; I carried one for 4 years (with 5 years of M16A2/A4 before that) including a year downrange during OIF1, but there is lots of room for improvement just to bring it up to modern standards. If the military were to ride out the M4 for another 10 years they should at least consider things like hammer forged barrels, Salt-Bath nitride for steel components, nickel teflon coatings for operating components, improved material selection for bolt/extractor, etc. I'd like to see a piston operating system as well, but I'll try and stay out of that arguement here...
Stephen
Stephen,
I totaly agree there is room for imrpovements with the M4, and any/every weapons system in general. I am not arguing against pistons, just stating my persoanl opinion on the "need" for a piston system in a DI gun that was not designed for one. For me I just can't see a reason to spend the extra money on a "problem" that isn't plaguing me personally; like I said if I could get my DI M4 to have a malfunction, I would have ahd the reasoning to go to the wife and get a piston rifle; but I couldn't find the reasoning personally. If there is a niche in the armed forces for such an application; then by all means they should adopt the platform. I am merely debating the reasoning behind the whole "Pistons are the greatest things ever and DI is awful" statements I see all the time all over the internet. One system is not superior to another, they have different applications, and different operating parameters.
Suffice it to say; piston systems are great; but they don't "fix" anything "wrong" with DI systems as most tout them to do, they just change the configuration of the rifle is all; a slight increase in reliability may be seen, but there isn't enough combat/field proven AR/piston systems data around to know that yet...
Both systems are very reliable and both will be around for a LONG time.
I would trust my life to either system, as long as it is a high quality rifle.
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