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TigerStripe
06-07-06, 12:04
What is your favorite piston upper or which do you think is the best?


TS

Daniel Defense
06-07-06, 12:14
POF makes an awesome piston upper.

After handling Larry Vickers HK 416 last month I really like it as well.

M4arc
06-07-06, 12:27
I think first and foremost I would love an HK416 but I doubt I’d ever be able to get my grubby little mitts on one. I have high hopes for the Colt LE1020 but they aren’t due out until the end of 2007 (the last I heard). The Leitner-Wise stuff is a mystery until they can get production up and fill in all the orders and complete their arfcom group buy.

That leaves me with the POF as the front runner but not by default mind you. There is an excellent thread over on 10-8 and I took it that Frank was on top of things and making changes based upon the feedback he was receiving. By the sounds of it he’s constantly making improvements and is open to suggestions. I was very impressed with POF after reading that thread and the comments from those in the know. Oh and he's listening to the right people as well.

In addition to that dport recently purchased one and he seems to be more than happy with his. If I was to buy one today, without a doubt I would buy a POF because it sounds like Frank is in the mix, putting out an excellent product and constantly looking to improve that product.

Griz
06-07-06, 12:41
I'm not convinced of the need for one yet....

At a recent machinegun shoot, my 10" AR with a RDIAS ran for about 2500 rounds of steel cased Wolf before it malfunctioned. The malfunction was so much red gunk had built up inside the bolt that the firing pin could no longer hit the primer.

I think that red gunk is the sealant around the primer pocket, so I'm not convinced that it came through the gas tube in the first place. I think it came through the firing pin hole so a piston upper would probably have the same problem.

Even if a piston would have run longer, I don't see hosing out my bolt every 2000+ rounds as a serious hardship. Maybe if I was on a 2-way range, but that's not gonna happen, and even if it did, I would try to avoid using the dirtiest ammo known to modern man. ;)

(I might still get a piston upper though just because it's another toy to put in my toy box, er, I mean my safe.)

Dport
06-07-06, 13:54
IIn addition to that dport recently purchased one and he seems to be more than happy with his. If I was to buy one today, without a doubt I would buy a POF because it sounds like Frank is in the mix, putting out an excellent product and constantly looking to improve that product.
Extremely happy is more like it.

And for those who may have heard, yes I did have a problem at a recent class. ONE OF MY OWN DOING.

A little history. I bought a stripped P-416 lower. Finished it out with CMT parts, and I put a SOPMOD stock on it. I did not torque the castle nut, nor did I stake it. Nor, it seems, did I screw the receiver extension in far enough to keep the buffer retainer in place. During a course of fire the buffer retainer worked loose and gummed up the works.

That problem WAS IN NO WAY ASSOCIATED WITH POF. That was a Dport screwup (bad, bad DPORT).

The POF assembled parts have functioned 100%.

I have another stripped lower that I'm considering a POF 18" upper for, sometime in the future. I am also very interested in their .308 gun.

I do still have my 16" Bushy superlight with an A1 upper, because the one thing the POF is not is superlight. I'm not sure you can get a piston gun as light as a DI gun. Although, if POF is willing to try, I'll be more than happy to beta test it.:D

SAW_5.56
06-07-06, 14:05
Extremely happy is more like it.

And for those who may have heard, yes I did have a problem at a recent class. ONE OF MY OWN DOING.

A little history. I bought a stripped P-416 lower. Finished it out with CMT parts, and I put a SOPMOD stock on it. I did not torque the castle nut, nor did I stake it. Nor, it seems, did I screw the receiver extension in far enough to keep the buffer retainer in place. During a course of fire the buffer retainer worked loose and gummed up the works.

That problem WAS IN NO WAY ASSOCIATED WITH POF. That was a Dport screwup (bad, bad DPORT).

The POF assembled parts have functioned 100%.

I have another stripped lower that I'm considering a POF 18" upper for, sometime in the future. I am also very interested in their .308 gun.

I do still have my 16" Bushy superlight with an A1 upper, because the one thing the POF is not is superlight. I'm not sure you can get a piston gun as light as a DI gun. Although, if POF is willing to try, I'll be more than happy to beta test it.:D

Minor thread hijack in progress: Dport, how do you like the POF lower? I'm looking at many different lowers in fear of the dems taking over in Nov. Does POF make it in house or is it subcontracted like Noveske/CMT, or RRA/CMT? How closely does the teflon finish match the anodizing of an upper?

Dport
06-07-06, 14:18
I've been through two different carbine classes with this one lower, one with a DI gun, one with a piston gun, if that matters to you. I've never had a problem with it. I do have one mag that won't drop free from it; however, I suspect that is because that mag is old, probably out of spec, and definitely needs replaced.

Call me a poser if you want, but I like the pictograms on it. And, IMO, the deep black finish is a plus. I was going to KG coat the lower, but I couldn't bring myself to do it.

I don't know if POF makes their own or what, I'll let them answer that question; however, I have not had any problems with fit, finish or function with their lower.

The only thing I know is I waited for my lowers, but they were worth it!

IndianaJeff
06-07-06, 16:12
I second the POF, I personally haven't used one but my shooting buddy has one, it's impressive how it works, just haven't talked myself in to one yet.

MAP
06-07-06, 17:05
POF makes an awesome piston upper.

After handling Larry Vickers HK 416 last month I really like it as well.

Jay,

Any chance a DD 7.0 can be made to fit the POF or Leitner Wise piston set ups?

Thanks,

Mike

VA_Dinger
06-07-06, 17:29
I would have to say the HK416 is the "Best" based on the extensive testing it has gone through by both HK and the Tier 1 units issuing it. I highly doubt if any other gas piston design has seen even 1/4 the testing. If the system had any fleas these guys would have found them long ago.

Having handled and shot both Larry’s & Simon’s HK416 several times it’s hard not to be impressed. I’m not a big “Fit & Finish” guy, but the HK is simply perfect. Both ran like a Swiss watch also.

That being said they are not available for us yet. State & local LE sales have started, and I do consider this to be a positive sign for the future.

As for the other designs I have heard good and bad things about all of them. I have personally seen both a POF & LW run fine through an entire class, and that was certainly encouraging to see. I have spoken with Paul from LW about driving up for a shoot and hopefully this will happen this summer. As M4arc stated the POF has been getting some good reviews lately. Dport seems to like his POF and I respect his opinion. I also find the Colt LE1020 very interesting; time will tell on how it performs. I look forward to getting some real experience with all of these designs.

cohiba
06-07-06, 17:33
Still believe that piston uppers are an answer to an as yet unclear question. If there are any benefits, they might only be appreciated by the most severe end user under equally severe conditions.

As a civilian shooter, even the most ammo happy training I have undergone burned about 2200 rds in short order. My well lubed M4 with good mags (HKs) never missed a beat. Any Tier 1 rifle that hiccupped was either dry or had a bad magazine.

I can't imagine a piston set up for me that would be better than what I require and get out of my Colt/Noveske/LaRue upper. I'll be seeing another piston upper competitor next month and while I'm sure it will shoot well, again, I do not think the gas impingement system as refined as it is now is in trouble any time soon. I have been wrong once though...well twice...there was that one time in 1985 but the less said about that the better. ;)

Daniel Defense
06-07-06, 17:39
Jay,

Any chance a DD 7.0 can be made to fit the POF or Leitner Wise piston set ups?

Thanks,

Mike

The piston uppers won't work with the current DD rails but we are working on something with the AR15 Lite Rail so that the POF piston upper would work with them.

Dport
06-07-06, 17:42
I would have to say the HK416 is the "Best" based on the extensive testing it has gone through by both HK and the Tier 1 units issuing it. I highly doubt if any other gas piston design has seen even 1/4 the testing. If the system had any fleas these guys would have found them long ago.
I don't think you can say any DI gun has undergone the testing a Colt or an FN has undergone either. You pay your money, and you take your chances.

The advantage of a civilian user of these guns is you can operate it until you feel comfortable with it, and if you have any problems you can send it back to be worked on. The advantage is you can get a gun in just about any configuration you want

I think military guns have to be totally different. You have to have high quality every time and be able to expect the gun to function very well for the projected life span of the gun. The price you pay is conformity. You don't get to pick and chose what you want or don't want.

VA_Dinger
06-07-06, 18:18
Still believe that piston uppers are an answer to an as yet unclear question. If there are any benefits, they might only be appreciated by the most severe end user under equally severe conditions.



I would have to agree 100%.

We have all seen properly maintained & lubricated standard AR's run fine even through some very high round counts. That being said the gas piston designs certainly give the end user more margin for error in keeping his weapon reliable.

TigerStripe
06-07-06, 19:02
I have a POF and love it. I don't care for the Predator rail on a "combat-style" carbine, for shooting targets it's fine. Good to hear DD is working on a rail to fit the POF. I'll be one of the first to snag one up.


TS

Harv
06-07-06, 19:06
I don't have any burning desire for a piston upper. I could see if my normal Upper was unreliable or did not function well. But I guess that's just me. if I had to have one I would love the HK416. But only if they made them reasonable in price.

SAW_5.56
06-07-06, 20:34
I would have to say the HK416 is the "Best" based on the extensive testing it has gone through by both HK and the Tier 1 units issuing it. I highly doubt if any other gas piston design has seen even 1/4 the testing. If the system had any fleas these guys would have found them long ago.

Having handled and shot both Larry’s & Simon’s HK416 several times it’s hard not to be impressed. I’m not a big “Fit & Finish” guy, but the HK is simply perfect. Both ran like a Swiss watch also.

That being said they are not available for us yet. State & local LE sales have started, and I do consider this to be a positive sign for the future.

As for the other designs I have heard good and bad things about all of them. I have personally seen both a POF & LW run fine through an entire class, and that was certainly encouraging to see. I have spoken with Paul from LW about driving up for a shoot and hopefully this will happen this summer. As M4arc stated the POF has been getting some good reviews lately. I also find the Colt LE1020 very interesting; time will tell on how it performs. I look forward to getting some real experience with all of these designs.

There is a thread over on 10-8 forums that I read recently with some interest. It was a thread on the POF piston system but a gentleman chimed in saying that the HK 416 couldn't beat the MK18 in recent testing concerning waterborne environments. The thread is still up, pretty sure it's not gunshop commando/mall ninja fare. If true it was kind of surprising.

C4IGrant
06-07-06, 20:46
There is a thread over on 10-8 forums that I read recently with some interest. It was a thread on the POF piston system but a gentleman chimed in saying that the HK 416 couldn't beat the MK18 in recent testing concerning waterborne environments. The thread is still up, pretty sure it's not gunshop commando/mall ninja fare. If true it was kind of surprising.

The Navy looks at different things than say the Army does. The HK failed the "over the beach test" from what I have heard from credible sources. I also think that if HK would have made some minor configuration changes (VERY MINOR) the 416 would have passed the Navy test.

With that being said, I have fired the 416 and LW systems. I found that they both had higher felt recoil to me. The 416 in particular felt overly heavy to me as well. The model I shot was their 10.5 so it was light as they could make it.

I am all for piston systems, but want them to be light weight and with little to no more recoil than a DI system. Until I see this happen, I will pass.


C4

SAW_5.56
06-07-06, 21:17
The Navy looks at different things than say the Army does. The HK failed the "over the beach test" from what I have heard from credible sources. I also think that if HK would have made some minor configuration changes (VERY MINOR) the 416 would have passed the Navy test.

With that being said, I have fired the 416 and LW systems. I found that they both had higher felt recoil to me. The 416 in particular felt overly heavy to me as well. The model I shot was their 10.5 so it was light as they could make it.

I am all for piston systems, but want them to be light weight and with little to no more recoil than a DI system. Until I see this happen, I will pass.


C4

When you say heavy, do you mean heavy as in overall weight? Or are you refering to balance, more front heavy?

JTAC_Supply
06-07-06, 21:18
While I like the idea of the piston guns, and have fired the POF and LW, and have friends that have and like the POF, the ones I've handled seemed pretty heavy in comparison to similar direct impingement guns. Certainly nothing against them, but I didn't like that aspect. Other than that, the current limitations of rail system availability is a bummer but I imagine that may change down the road as the systems mature.

That said, I keep planning on getting a POF to play with but haven't gotten around to it yet.

Jason

knobcreek
06-07-06, 21:53
What is your favorite piston upper or which do you think is the best?


TS

I've only shot one "modern" AR gas piston rifle, the one I own. It's a Leitner-Wise. I can't comments on it being "better" than any of the others as I've never run the others through the ringer myself. That said, I like what I own quite a bit....functions flawlessly, runs cooler and cleaner that a DI weapon. It's not the end-all but a nice improvement/enhancement to an already sound system.

olds442tyguy
06-08-06, 17:31
Word has it that LMT is making a piston drive set up for the MRP too.

This of course stems from a random ArfCommer, so I figure if no one else has heard anything about it that I'll contact LMT later to get some details.

Hearing that DD is working with POF really gets my hopes up. The POF system appears to be good to go already, but the added strength and lightweight of the DD rails would be a huge plus.

C4IGrant
06-08-06, 17:59
When you say heavy, do you mean heavy as in overall weight? Or are you refering to balance, more front heavy?


Overall weight. I think the barrel was an HBAR and the rail system seemed OVERLY thick (which greatly added to the weight).



C4

Dport
06-08-06, 18:09
With that being said, I have fired the 416 and LW systems. I found that they both had higher felt recoil to me. The 416 in particular felt overly heavy to me as well. The model I shot was their 10.5 so it was light as they could make it.
C4
I think I shot the same 416, and noticed the increased recoil compared to my memory of our M4A1s.

The POF, on the other hand, seemed like it had less recoil than my DI gun. Don't know why. Recoil is so subjective it's hard to know exactly why. Might have been just the weight of the gun compared to my DI gun.

C4IGrant
06-08-06, 19:26
I think I shot the same 416, and noticed the increased recoil compared to my memory of our M4A1s.

The POF, on the other hand, seemed like it had less recoil than my DI gun. Don't know why. Recoil is so subjective it's hard to know exactly why. Might have been just the weight of the gun compared to my DI gun.

I have not fired a POF so it might be totally different.



C4

txswat
06-08-06, 20:17
I have been using a POF upper for several months and it runs great. I also felt that the recoil was less also. It actually felt like it recoiled straight back. My times were a little faster.

Dport
06-08-06, 20:35
It actually felt like it recoiled straight back.
That is how I perceived the recoil as well.

Damon
06-09-06, 08:36
I have spoken with Paul from LW about driving up for a shoot and hopefully this will happen this summer.

Dinger,

Let me know if and when you come up. We can get together. I live near the L-W address.

VA_Dinger
06-09-06, 08:42
Dinger,

Let me know if and when you come up. We can get together. I live near the L-W address.


10-4, that sounds like a great idea.

I also planning on begging Dport to test out his POF during our next class together. :D

Stickman
06-09-06, 23:31
What is your favorite piston upper or which do you think is the best?


TS




Aside from the little issue, are you still liking yours?

TigerStripe
06-10-06, 01:01
Aside from the little issue, are you still liking yours?


Since then I haven't had a single problem. It has 2500+ rounds through it now and has only been cleaned twice. It shoots much more accurately than I personally can. The one and only thing that kinda gets to me now is the width of the Predator rail. It's a good rail just a little too wide. I have attached a G2 light (on my DI M4) and I just use the push button on the back to activate it. I had problems with pressure switch lights coming on when they come on sometimes when they shouldn't. All this to say that I can't do that with my POF with the P4X rail. Hopefully DD will come out with a rail to fit the POF. I have a DD 7.0 on my (DI) M4 and it's the shizzle. Thanks!

TS

Stickman
06-10-06, 10:49
The width of the rail seems to be the largest complaint, but I'm not sure how much clearance they have available to slim it out. I have to agree that the DD rails just feel "right" in my hands.

M4arc
06-10-06, 11:01
Hopefully Frank will be along with his photos but in a thread on another forum he stated that they are working on the width of the rail (among other things) and that they were looking into using standard handguards as well!

TigerStripe
06-10-06, 16:18
Hopefully Frank will be along with his photos but in a thread on another forum he stated that they are working on the width of the rail (among other things) and that they were looking into using standard handguards as well!

They do have a P12X-S (I believe that's it) that is slimmer that the P4X and P9X, but lacks a lot of rail space. If you buy the P415/416 that uses M4 handguards you can install the Troy/Samson rails (with some modification) because they use the standard barrel nut. I believe that two piece rails like MI rails can be used but I'm not sure. If they came out with a version with a smaller rail, such as a DD, the sales would go through the rough. The only reason I can think of for not going to a smaller rail would be heat. My POF is much cooler after shooting than my M4.



TS

Stickman
06-11-06, 12:01
POF has said that DD is working on a rail, so changes a lot of things for me. A piston upper that is slim makes it much more interesting......



I'll probably end up with one if and when this ends up with the new rail. Hell, I'll probably end up T&Eing one for the department, then buy it if possible. Most of the teams are starting to move away from HK 5.56 weapons, and a piston upper may be something that could be highly useable for them when they make the switch to the M16 platform.

mr h
06-12-06, 15:32
i have a POF 11.5 upper with the M4 hg's, not the predator rail. i feel like the recoil was very similar to the recoil from my 11.5" DI gun that has a standard gas tube. on my other 11.5 upper i have a fat boy gas tube. i think the felt recoil is lighter on the fat boy gas tubed DI upper.

i am waiting to get my POF upper back from frank now. he is upgrading the barrel nut to the new design that is like the original barrel nut and will allow the use of the more common rails, as soon as someone makes one to fit over the top of the gas tube. hint hint, DD.

Lumpy196
06-14-06, 02:19
With that being said, I have fired the 416 and LW systems. I found that they both had higher felt recoil to me.
C4


A lot of people get bent when I mention piston-systems and "pogo stick" in the same sentence....

:cool:

TigerStripe
06-14-06, 10:01
A lot of people get bent when I mention piston-systems and "pogo stick" in the same sentence....

:cool:

My POF has less recoil than my M4. Also you can run a 9mm buffer, an Enidine or an MGI buffer. I have run mine with an H2 buffer that can with it, a 9mm buffer and an Enidine. The (mm and the Enidine are close but the Enidine works best. The recoiland muzzle flip were less than a DI M4 with just the H2 buffer.


TS

MP5 Machinenpistole
06-15-06, 19:35
In my experience (military, law enforcement, and civilian), I am not sure what problem(s) the gas-piston operated upper receivers are supposed to solve.

I have Lewis Machine and Tool (LMT) Monolithic Rail platform (MRP) upper receivers on all three of my Class 3 M4 carbines and all have worked great without any stoppages or malfunctions; total round count approaching 6,200 on each receiver.

Given an excellent quality manufactured carbine or rifle (Colt, LMT, Noveske, etc.), good quality ammunition (Federal M193 Brown Box my favorite), and excellent condition magazines (New / excellent condition GI magazines with Magpul followers and Specialized Armament Red Springs or HK SA 80) and I very doubtful that the gas-piston uppers will function any better than the current gas-direct systems.

Aside from the gas-piston uppers being easer to clean, I do not see any advantage. I think many AR users think that a gas-piston upper will solve a problem that they really do not have, or could be solve with them using good quality parts, ammunition, and magazines.

VA_Dinger
06-17-06, 04:36
In my experience (military, law enforcement, and civilian), I am not sure what problem(s) the gas-piston operated upper receivers are supposed to solve.

I have Lewis Machine and Tool (LMT) Monolithic Rail platform (MRP) upper receivers on all three of my Class 3 M4 carbines and all have worked great without any stoppages or malfunctions; total round count approaching 6,200 on each receiver.

Given an excellent quality manufactured carbine or rifle (Colt, LMT, Noveske, etc.), good quality ammunition (Federal M193 Brown Box my favorite), and excellent condition magazines (New / excellent condition GI magazines with Magpul followers and Specialized Armament Red Springs or HK SA 80) and I very doubtful that the gas-piston uppers will function any better than the current gas-direct systems.

Aside from the gas-piston uppers being easer to clean, I do not see any advantage. I think many AR users think that a gas-piston upper will solve a problem that they really do not have, or could be solve with them using good quality parts, ammunition, and magazines.


Marketing BS aside, the true advantages of the gas piston guns will show itself on SBR AR's (10.5"-14.5"). Short barreled AR's are certainly a compromise. You get a lighter and more compact weapon, but you lose some reliability. Gas piston systems alleviate this. On 16” or longer barrels most of us would never see the difference.

POF-USA
06-18-06, 10:19
They do have a P12X-S (I believe that's it) that is slimmer that the P4X and P9X, but lacks a lot of rail space. If you buy the P415/416 that uses M4 handguards you can install the Troy/Samson rails (with some modification) because they use the standard barrel nut. I believe that two piece rails like MI rails can be used but I'm not sure. If they came out with a version with a smaller rail, such as a DD, the sales would go through the rough. The only reason I can think of for not going to a smaller rail would be heat. My POF is much cooler after shooting than my M4.



TS

TigerStripe,

We also offer our slim version of our Predator rail system in carbine, and mid-length also.

Our slim Predator models are:
P-4SX
P-9SX
P-12SX

Best regards,

Frank
Patriot Ordnance Factory (http://www.pof-usa.com)

PS: you are correct. Our rail design is to help reduce heat quickly and to help prevent flex in the flat top receiver. :D

twl
06-22-06, 09:39
I don't really have any "dog in this fight", but as far as I'm concerned people should get what they think is best.

Personally, my opinion is that the Stoner Gas System is a very good system that has proven itself to be a highly capable system that basically is the "de-facto" standard in allied military weaponry in combat, also totally rules the competition circuits, and is one of the most popular commercial systems for many reasons.

There are some very sound design principles employed in the Stoner Gas System, as applied in the AR15/M16/M4, which we may not want to discard, simply because we think we might not have to clean our guns as often.

One of the weak points in the Stoner design is the accumulation of carbon and lubrication sludge in the bolt/carrier area over a large number of rounds fired.
That's what people don't like about it.
ANY external piston system will keep this area more clear of carbon.
However, you lose the optimal inline forces all being generated along the bore axis line, and now you have reciprocating mass above the barrel(along with all the things that come with that).
And you also lose the direct-inline carrier thrust that the Stoner System has, and have various angular force vectors acting on the carrier, from the overhead op-rod that is not axial with the boreline.
Then, it becomes a game of how well the piston-system designer tries to overcome these new problems introduced when the gas system is changed. How well he does that will determine how good that that system is.

There is no "panacea" in designs.
You simply trade one set of weak-points for another set of weak points, in order to get what you want. But when you do that, you also may trade away some strong points that you might really rather keep.

If anyone is thinking that it is all gain, and no loss, to change that gas system, then more study is required.

TigerStripe
06-23-06, 11:53
The main weak point of the direct impingement AR design is, and always has been, the need to regularly clean it. By regularly I mean more than any other battle weapon out there. The strength is accuracy, which it excels at. My experience with my POF has shown me than any accuracy loss is minimal, if any. The amount of cleaning necessary for my POF is negligible. Most cleaning that I have done was to remove the red Wolf primer sealant. Is it perfect? No. But the advantages look to me to outweigh the disadvantages. JMO, JME.

TS

quikStix
06-26-06, 15:21
Edited for trolling.

VA_Dinger
06-26-06, 15:58
I always find it odd that people run with even the tiniest bit of information.

Anybody who has a clue realizes that the HK416 is the most thoroughly tested AR gas piston design available. It is already in service with many of our most elite and secretive military units. Many of us have experienced first hand the shooting abilities and knowledge these men process. If the HK416 had any fleas these guys would be the first to know. One negative NSW opinion does not change that fact. That is the one and only negative end user post you will find. Hell, even the Navy’s top team is buying them now. I think the "Over-The-Beach" capabilities have been improved with the fully supported cartridge case bolt face. I don't know how "New" this improvement really is, but HK mentions it in their new brochure.

By the way, this forum is not going to allow any BS marketing. Bad mouthing the HK for the benefit of a competitor or at least likes to think of themselves as a competitor is not going to be allowed.

Post what you personally know or can prove. Anything else is going to be history.

Hoplophile
06-27-06, 00:49
I'm not convinced of the need for one yet....

At a recent machinegun shoot, my 10" AR with a RDIAS ran for about 2500 rounds of steel cased Wolf before it malfunctioned. The malfunction was so much red gunk had built up inside the bolt that the firing pin could no longer hit the primer.

I think that red gunk is the sealant around the primer pocket, so I'm not convinced that it came through the gas tube in the first place. I think it came through the firing pin hole so a piston upper would probably have the same problem.
I've had this happen to my Beretta 92FS after a few hundred rounds of WWB, so it's clearly not the gas system. :cool:

CapnCrunch
06-27-06, 06:42
Griz, just for the record, I had that same thing happen to my SAR3 and the Valmet. That sealant is some nasty crap.

Yojimbo
06-27-06, 08:15
How long can a piston upper go without any maintenance on the piston system? Will it eventually start having malfunctions or stop functioning after x amount of rounds?

MAP
06-27-06, 14:48
How long can a piston upper go without any maintenance on the piston system? Will it eventually start having malfunctions or stop functioning after x amount of rounds?

My understanding is that an H&K 416 went better that 25K rounds without failure or cleaning. I don't know about the POF or LW.

Mike

Dport
06-27-06, 14:52
How long can a piston upper go without any maintenance on the piston system? Will it eventually start having malfunctions or stop functioning after x amount of rounds?
Send me ammo and I'll tell you.:D

S-1
06-27-06, 19:58
I always find it odd that people run with even the tiniest bit of information.

Anybody who has a clue realizes that the HK416 is the most thoroughly tested AR gas piston design available. It is already in service with many of our most elite and secretive military units. Many of us have experienced first hand the shooting abilities and knowledge these men process. If the HK416 had any fleas these guys would be the first to know. One negative NSW opinion does not change that fact. That is the one and only negative end user post you will find. Hell, even the Navy’s top team is buying them now. I think the "Over-The-Beach" capabilities have been improved with the fully supported cartridge case bolt face. HK mentions this improvement in their new brochure.

By the way, this forum is not going to allow any BS marketing. Bad mouthing the HK for the benefit of a competitor or at least likes to think of themselves as a competitor will not be allowed. Post what you personally know or can prove. Anything else is going to be history.

I don't doubt the HK416 is the shit but, my LMT upper has been 100% and that is hard to improve on. LMT knows how to make the short guns run right and they're as battle tested/proven (if not more) than the HK416.

VA_Dinger
06-27-06, 21:59
I don't doubt the HK416 is the shit but, my LMT upper has been 100% and that is hard to improve on. LMT knows how to make the short guns run right and they're as battle tested/proven (if not more) than the HK416.


I certainly agree to a point.

My personal LMT 10.5" has been stone reliable through roughly 5,000 rounds over the past fourteen months. I take great care in the maintenance, cleaning, and lubrication of my 10.5". I also researched enough to learn the most reliable SBR set-up (HD extractor spring, CRANE o-ring, H2 buffer, all with periodic spring replacements based on round count). In short, I treat it like my custom 1911. I think if you get a good 10.5” out of the box and treat it right they can be very reliable weapons. Get a questionable weapon and treat it poorly and you are asking for trouble. That being said, the HK416 does not need such meticulous care to stay 100% reliable. Like I posted earlier in this thread, "Most of us would never notice a gas piston AR's advantages". This is certainly even more so on 14.5" and up barrel length AR's. The longer the barrel the more reliable the AR, it’s a simple undeniable fact.

For the Pro’s who take SBR AR’s into harms way the gas piston guns like the HK416 make perfect sense. They get a short/handy, yet still 100% reliable weapon. For the rest of us, it’s just an added piece of mind.

S-1
06-27-06, 23:31
I certainly agree to a point.

My personal LMT 10.5" has been stone reliable through roughly 5,000 rounds over the past fourteen months. I take great care in the maintenance, cleaning, and lubrication of my 10.5". I also researched enough to learn the most reliable SBR set-up (HD extractor spring, CRANE o-ring, H2 buffer, all with periodic spring replacements based on round count). In short, I treat it like my custom 1911. I think if you get a good 10.5” out of the box and treat it right they can be very reliable weapons. Get a questionable weapon and treat it poorly and you are asking for trouble. That being said, the HK416 does not need such meticulous care to stay 100% reliable. Like I posted earlier in this thread, "Most of us would never notice a gas piston AR's advantages". This is certainly even more so on 14.5" and up barrel length AR's. The longer the barrel the more reliable the AR, it’s a simple undeniable fact.

For the Pro’s who take SBR AR’s into harms way the gas piston guns like the HK416 make perfect sense. They get a short/handy, yet still 100% reliable weapon. For the rest of us, it’s just an added piece of mind.

My current LMT upper has a lot more rounds through it than yours and has also been VERY reliable. I run the same exact set-up in both my M4 and CQBR. Both have a Crane O-Ring and H Buffer, that's it. I clean them exactly the same, the short upper doesn't get "special treatment" from me or anyone else I know for that matter. My LMT has actually been more reliable than the M4. From what I have experienced, the LMT does not need to be maintained "meticulously" to perform reliably and I've seen, let's say, less than "sub-standard":eek: cleaning methods used on them but they still run great.

The same "Pro's" that you are talking about having the need for the piston uppers, because of maintenence issues, carry custom 1911's:confused:. The folks that are issued the LMT's are very happy with the performance of them.

Dport
06-28-06, 07:07
I think we have glossed over or totally missed the main advantage of a piston upper: heat.

During HK's testing of their piston design they found that even an unmodified bolt will last longer because of the lack of heat inherent in the piston design.

As Dinger said, most of us will never notice. However, if you're prone to using your SBR as a supressive fire type weapon you may.

Personally, I'll stick to my POF. I like having a gun that can be maintained like a Glock.

C4IGrant
06-28-06, 08:27
My current LMT upper has a lot more rounds through it than yours and has also been VERY reliable. I run the same exact set-up in both my M4 and CQBR. Both have a Crane O-Ring and H Buffer, that's it. I clean them exactly the same, the short upper doesn't get "special treatment" from me or anyone else I know for that matter. My LMT has actually been more reliable than the M4. From what I have experienced, the LMT does not need to be maintained "meticulously" to perform reliably and I've seen, let's say, less than "sub-standard":eek: cleaning methods used on them but they still run great.

The same "Pro's" that you are talking about having the need for the piston uppers, because of maintenence issues, carry custom 1911's:confused:. The folks that are issued the LMT's are very happy with the performance of them.

The 1911 is a secondary weapon. It also the most accurate HG made to date



C4

yrac
06-28-06, 10:32
The same "Pro's" that you are talking about having the need for the piston uppers, because of maintenence issues, carry custom 1911's:confused:. The folks that are issued the LMT's are very happy with the performance of them.

The Tier 1 units aren't carrying the piston SBRs for the easier maintenance. I don't believe those units have trouble with regular weapons maintenance. If the piston guns are more forgiving in terms of lubrication/cleaning, that is just a side benefit that might have applicability for longer barreled guns for general issue in the future.

I have seen 10.5" guns that run very well. (Including guns owned by members of this forum.) However, it is my understanding (from speaking with folks who know much more about it than I), that when issued in very large numbers, SBR's based on the direct impingement system exhibit a higher malfunction rate than guns with barrels of at least 14.5", and based on the same gas system. This higher malfunction rate has been deemed to be unacceptable by certain units.

I am not saying that nobody owns a 10.5" traditional upper that functions reliably - lots of folks do. What I am saying is that, if one looks at a sample of, say, 5000 10.5" guns and 5000 14.5" guns, all based on direct impingement, past experience indicates that the short gun group will have a higher incidence of "problem" guns. When issued in large numbers, it becomes very costly to troubleshoot the larger number of problem short guns. (Whereas it's no problem for an individual owner to spend a little time and money getting the gun to run properly.)

The gas piston system of the HK in short barreled weapons has been observed to greatly reduce the rate of occurrence of "problem guns" with barrels under 14.5". This cuts down on toubleshooting costs, and also (I would assume) greatly increases the peace of mind of a person who must carry a short barreled gun, and who will probably die if that gun doesn't go bang every time.

In short, if a piston gun requires less maintenance, that's just an added plus for the Tier 1 folks. The main advantage of the system is that it results in improved reliability with short barreled weapons when issued in large numbers.

Echoing Grant's comments above re the 1911 - certain units have a much higher accuracy/skill standard than that generally required throughout the military. These units, when they have chosen a 1911, have chosen it because it is an inherently accurate platform that meets their requirements. They have chosen this platform with the understanding that it WILL require a little more maintenance TLC than other platforms.


ETA:
S-1 - this wasn't directed specifically as any type of slam at you, so I hope it doesn't come across that way. Your comment above just served as a useful starting point for my thoughts when I posted.

twl
06-28-06, 12:25
Some comments regarding the heat issue.

The heat and volume of the combustion gasses is the same with either a piston-operating system or a Stoner Gas System.

But, the place that the gas goes, and is vented to, is different between these two systems.

Obviously, in a piston-operating system, hot gas does not go into the bolt/carrier area, and that is an advantage for extended bolt life.

However, the heat and gasses do go somewhere.
And where does the heat go, in most piston-operating systems?
It goes under the handguards.

Now, the barrel is under the handguards, and the hottest part of the barrel that needs the most cooling is under the handguards. Since the over-riding factor in cooling is the temp delta, raising the temps in the air surrounding the hottest part of the barrel could be considered quite a drawback.

In fact, it could be a type of drawback that could manifest itself much faster than the eventual weakening of a bolt from heat. It could become apparent as a cookoff situation at a much lower round count than a system with cooler air around the barrel under the handguards. And it could even happen in the very first fire-fight that the gun is involved in.

So again, we need to look at all sides of the things that are changed when we change the gas system, and not just the "rosy side of the story" that we might want to look at.

Unfortunately, the gas piston operating system has been surrounded by so much hyperbole lately, that having a serious discussion has been nearly impossible. This is largely due to some marketing efforts that have sought to demonize the Stoner Gas System as a "relic" or something that "needs to be replaced", in order to make room in the market for their "magic cure". It has become a "bandwagon" issue, with a bunch of cheerleaders.

In the final analysis, the decision is based on what weak points the user is willing to accept, in order to get what he wants. And there are weak points to both these systems, even though the cheerleaders will try to claim that there are no weak points to "their favorite" piston operating system.

You pays your money, and you takes your choice.

Edited to add:
There are some forms of piston-operating systems that are gas trap types, and do not vent much or any gas into the handguard area, and I think that possibly the POF, and maybe the HK 416 system may fall into this category. But they have the added weight, and the reciprocating mass above the boreline issue to deal with. Again, nothing is perfect, and I'd be in favor of getting all the pros and cons out on the table, for all the forms of gas systems for the AR.

Griz
06-28-06, 12:43
I think we have glossed over or totally missed the main advantage of a piston upper: heat.

Has anyone actually measured and published temp numbers for a bolt in an offset piston setup vs a DI gun?

If not, does anyone near Christiansburg, VA have an offset piston upper? I have an infrared thermometer as well as thermocouples. We could quickly determine if this is actually a real issue or just marketing FUD.

Dport
06-28-06, 12:48
Some comments regarding the heat issue.

The heat and volume of the combustion gasses is the same with either a piston-operating system or a Stoner Gas System.

But, the place that the gas goes, and is vented to, is different between these two systems.

Obviously, in a piston-operating system, hot gas does not go into the bolt/carrier area, and that is an advantage for extended bolt life.

However, the heat and gasses do go somewhere.
And where does the heat go, in most piston-operating systems?
It goes under the handguards.

Now, the barrel is under the handguards, and the hottest part of the barrel that needs the most cooling is under the handguards. Since the over-riding factor in cooling is the temp delta, raising the temps in the air surrounding the hottest part of the barrel could be considered quite a drawback.
In fact, it could be a type of drawback that could manifest itself much faster than the eventual weakening of a bolt from heat. It could become apparent as a cookoff situation at a much lower round count than a system with cooler air around the barrel under the handguards. And it could even happen in the very first fire-fight that the gun is involved in.
Could be. However, I haven't noticed it in shooting my POF. And if it was a serious disadvantage I'm sure H&K would have uncovered it in their extensive testing of the 416. The last number I heard was that H&K's testing alone was in the neighborhood of 250,000 rounds. I'm sure I'm lowballing that. Specifically, cookoffs didn't seem to be a problem.

You have a lot of "could"s there. Do you have some personal experience or are you just theorizing?

The great thing about hot gases under the handguards, in my experience, is they have some place to go. Luckily a combination of ventilated handguards and the fact that heat rises helps greatly.




So again, we need to look at all sides of the things that are changed when we change the gas system, and not just the "rosy side of the story" that we might want to look at.
And we shouldn't be frightened into inaction by fear of "could"s. Could isn't will.


Unfortunately, the gas piston operating system has been surrounded by so much hyperbole lately,
On both sides.


that having a serious discussion has been nearly impossible.
I have had serious discussions about gas piston uppers with people who helped design them and with people who were conducting extensive testing of them for .gov agencies.


This is largely due to some marketing efforts that have sought to demonize the Stoner Gas System as a "relic" or something that "needs to be replaced", in order to make room in the market for their "magic cure". It has become a "bandwagon" issue, with a bunch of cheerleaders.
Of course, some of us are cheerleading because we've had first hand experience. Do you?


In the final analysis, the decision is based on what weak points the user is willing to accept, in order to get what he wants. And there are weak points to both these systems, even though the cheerleaders will try to claim that there are no weak points to "their favorite" piston operating system.

You pays your money, and you takes your choice.
I have yet to see someone here say the Stoner system is a relic. Maybe you're confusing this with another website.

Dport
06-28-06, 13:04
Has anyone actually measured and published temp numbers for a bolt in an offset piston setup vs a DI gun?

If not, does anyone near Christiansburg, VA have an offset piston upper? I have an infrared thermometer as well as thermocouples. We could quickly determine if this is actually a real issue or just marketing FUD.
I don't know the exact temperature. However, I have one DI gun and one piston gun. I empty a 30 round mag from the DI gun and the bolt is hot. I empty a 30 round mag from the piston gun and the bolt is cool. :)

My info about the heat and the bolt breakage was from someone who was involved in the HK416 testing.

twl
06-28-06, 13:23
Could be. However, I haven't noticed it in shooting my POF. And if it was a serious disadvantage I'm sure H&K would have uncovered it in their extensive testing of the 416. The last number I heard was that H&K's testing alone was in the neighborhood of 250,000 rounds. I'm sure I'm lowballing that. Specifically, cookoffs didn't seem to be a problem.

You have a lot of "could"s there. Do you have some personal experience or are you just theorizing?

The great thing about hot gases under the handguards, in my experience, is they have some place to go. Luckily a combination of ventilated handguards and the fact that heat rises helps greatly.



And we shouldn't be frightened into inaction by fear of "could"s. Could isn't will.

On both sides.

I have had serious discussions about gas piston uppers with people who helped design them and with people who were conducting extensive testing of them for .gov agencies.

Of course, some of us are cheerleading because we've had first hand experience. Do you?

I have yet to see someone here say the Stoner system is a relic. Maybe you're confusing this with another website.

Okay,
"Coulds" are what can happen in the real world, and they have to be considered as a possiblity, when designing.

You may note that in my edited addendum, I mentioned that POF (and HK) may fall into the category that doesn't vent as badly under the handguard. I haven't had a 416 actually in my hands, ever.

Regarding "theorizing", or "personal experience", I am an assistant weapons designer with MGI, under Mack Gwinn, for more than 6 years. We design and manufacture AR15 variant, and performance accessory products, and MGI has previously worked in partnership with Jim Sullivan, one of the key members of the original Armalite AR-15 design team and the highest ranking member of that design team still alive.
I also work closely with ABS barrels, as a consultant, and they are one of the most "cutting edge" barrel technology makers at this time.
So, I suppose you could say that I "theorize", and then bring those theories into development and production, as "personal experience". Including understanding the surrrounding issues of the designs, and the ramifications thereof.

The "great thing about hot gas under the handguards" is not so great.
Raising the air temp around the barrel, which WILL occur when extremely hot gas is repeatedly vented into that area, decreases the temp delta, which WILL result in poorer barrel cooling. This is basic thermodynamics. Heat rising is also basic thermodynamics, but repeated hot gas injections from repeated firings make that point moot in a system which vents gas under the handguards The temp delta will be decreased in repeated firings.

"Frightening" is not my intent. My intent is to bring all aspects of these designs to light, for rational analytical analysis by the forum members. I personally don't have any concern which system people might think is best, but would like discussion that brings up pros and cons of all the contending designs for the AR.

First hand experience, I've had. Also I've owned many piston-operated designs in the past. The company I work for made its first piston operated AR-variant in the 1970's. We know about them. I don't claim to have shot all the piston operated AR15 variants, but I know designs and applied science and firearms design first hand, and I can discuss these issues from that viewpoint, in addition to the experience I have had. And yes, the POF system is one that I have shot, and have customers and friends who also have shot the POF system. That includes the owner of ABS barrels, who is a personal friend of Bob Davies, who originated the first early version of the POF system. That system was successfully used on an early test of the ABS barrels for "torture test" purposes. The POF system has alot going for it.

Regarding the term "relic', yes I'm referring primarily to alot of the talk on other website boards, including probably the board you are thinking of.

Of course, if my experience and comments are unwelcome here, I'd be amenable to ceasing participation on the board, except if direct questions come up about the products that my company affiliates make.

Dport
06-28-06, 14:23
Okay,
Of course, if my experience and comments are unwelcome here, I'd be amenable to ceasing participation on the board, except if direct questions come up about the products that my company affiliates make.
That was not my intent at all. I look forward to learning from your experiences.

S-1
06-28-06, 14:35
The Tier 1 units aren't carrying the piston SBRs for the easier maintenance. I don't believe those units have trouble with regular weapons maintenance. If the piston guns are more forgiving in terms of lubrication/cleaning, that is just a side benefit that might have applicability for longer barreled guns for general issue in the future.

I have seen 10.5" guns that run very well. (Including guns owned by members of this forum.) However, it is my understanding (from speaking with folks who know much more about it than I), that when issued in very large numbers, SBR's based on the direct impingement system exhibit a higher malfunction rate than guns with barrels of at least 14.5", and based on the same gas system. This higher malfunction rate has been deemed to be unacceptable by certain units.

I am not saying that nobody owns a 10.5" traditional upper that functions reliably - lots of folks do. What I am saying is that, if one looks at a sample of, say, 5000 10.5" guns and 5000 14.5" guns, all based on direct impingement, past experience indicates that the short gun group will have a higher incidence of "problem" guns. When issued in large numbers, it becomes very costly to troubleshoot the larger number of problem short guns. (Whereas it's no problem for an individual owner to spend a little time and money getting the gun to run properly.)

The gas piston system of the HK in short barreled weapons has been observed to greatly reduce the rate of occurrence of "problem guns" with barrels under 14.5". This cuts down on toubleshooting costs, and also (I would assume) greatly increases the peace of mind of a person who must carry a short barreled gun, and who will probably die if that gun doesn't go bang every time.

In short, if a piston gun requires less maintenance, that's just an added plus for the Tier 1 folks. The main advantage of the system is that it results in improved reliability with short barreled weapons when issued in large numbers.

Echoing Grant's comments above re the 1911 - certain units have a much higher accuracy/skill standard than that generally required throughout the military. These units, when they have chosen a 1911, have chosen it because it is an inherently accurate platform that meets their requirements. They have chosen this platform with the understanding that it WILL require a little more maintenance TLC than other platforms.


ETA:
S-1 - this wasn't directed specifically as any type of slam at you, so I hope it doesn't come across that way. Your comment above just served as a useful starting point for my thoughts when I posted.

The 10.5" LMT is issued to NSW in LARGE numbers and has performed great. The reliabilty of the LMT has actually been better than the Colt M4's. So, I think that 10.5 vs 14.5 reliability is a moot point.

What is the cost going to be when the HK416's go down? Will spare parts be available in mass like the DI guns? Just because a a ceratin Tier 1 unit adopts the HK416 doesn't mean anything to me. It says that the gun is reliable, but so is my Mk18.

FWIW. I was shooting with some folks and the guy next to me was, let's say, supposed to be "higher speed" than me and he acted like it too. He had a M4 w/ a S&B Short Dot and the rest of the goodies. This guy was also carrying a custom 1911. I was on the line with my CQBR w/ M68, LMT buis ect ect and my Sig P226.

I out shot him on both the pistol and rifle course. I was quite surprised (not really ;) ). I thought for sure he was going to get me in the rifle course because of his variable S&B. I think I humbled him a bit. All he had to say was "good shootin" and walked away.

Moral of the story. Super Megaforce Upper with Super Custom 1911 doesn't make you a better shooter.

Grant.... since the 1911 is the most accurate handgun to date, how come my 226 out shot it?

VA_Dinger
06-28-06, 15:12
Moral of the story. Super Megaforce Upper with Super Custom 1911 doesn't make you a better shooter.

Grant.... since the 1911 is the most accurate handgun to date, how come my 226 out shot it?

Obviously, you are correct.

I don't think anybody posting in this thread is implying that either. What we are saying is "Better" equipment gives more potential accuracy. Having a Short Dot for example just gives a shooter more options and capabilities. The 1911 handgun has more inherent accuracy merely by design. I think everybody understands the difference and that the shooter is still the most important part of the equation. Trust me, several of us in this thread have seen a certain shooter make a Sig dance. I could not out shoot him on my best day even if he was sick in bed. Yrac himself can out shoot most guys with his bone stock G19. I have seen it many times. Equipment does not make holes in the X or bad guys bleed out any faster and I think everybody understands that fact. At least in this thread.

C4IGrant
06-28-06, 16:41
The 10.5" LMT is issued to NSW in LARGE numbers and has performed great. The reliabilty of the LMT has actually been better than the Colt M4's. So, I think that 10.5 vs 14.5 reliability is a moot point.

What is the cost going to be when the HK416's go down? Will spare parts be available in mass like the DI guns? Just because a a ceratin Tier 1 unit adopts the HK416 doesn't mean anything to me. It says that the gun is reliable, but so is my Mk18.

FWIW. I was shooting with some folks and the guy next to me was, let's say, supposed to be "higher speed" than me and he acted like it too. He had a M4 w/ a S&B Short Dot and the rest of the goodies. This guy was also carrying a custom 1911. I was on the line with my CQBR w/ M68, LMT buis ect ect and my Sig P226.

I out shot him on both the pistol and rifle course. I was quite surprised (not really ;) ). I thought for sure he was going to get me in the rifle course because of his variable S&B. I think I humbled him a bit. All he had to say was "good shootin" and walked away.

Moral of the story. Super Megaforce Upper with Super Custom 1911 doesn't make you a better shooter.

Grant.... since the 1911 is the most accurate handgun to date, how come my 226 out shot it?


To quote Steve of ADCO, it is always the singer and not the song. Meaning that if your a better shot then your a better shot. No piece of gear will make up the difference.

And yes, the 1911 is more accurate than the 226.


C4

VA_Dinger
06-28-06, 16:51
Okay,
Of course, if my experience and comments are unwelcome here, I'd be amenable to ceasing participation on the board, except if direct questions come up about the products that my company affiliates make.

Trust me, experts like you are more than just encouraged to post on M4carbine. This is not going to be just another forum. We consider industry experts like you to be the backbone of this forum. We will obviously have disagreements from time to time, but everybody will keep it calm, polite, and professional. We are not going to have the moronic mob tactics you commonly see elsewhere.

VA_Dinger
07-10-06, 16:25
Heads Up:

Ken Hackathorn just wrote a new article for Special Weapons for Military & Police magazine on the HK416.

Free PDF version of the article:
http://www.vickerstactical.com/articles/HK416_556mm.pdf

Very interesting to say the least.

variablebinary
08-08-06, 13:36
I'm waiting to see how the SIG 556 appears, but I am very interested in piston uppers, and would probably go with POF in the absence of HK, as there are still too many questions surrounding Colt LE1020.

I've never really liked direct fouling, even if in practice it doesnt really hamper performance.

Griz
08-08-06, 15:27
Raising the air temp around the barrel, which WILL occur when extremely hot gas is repeatedly vented into that area, decreases the temp delta, which WILL result in poorer barrel cooling. This is basic thermodynamics. Heat rising is also basic thermodynamics, but repeated hot gas injections from repeated firings make that point moot in a system which vents gas under the handguards The temp delta will be decreased in repeated firings.


Has anyone quantified this effect? Obviously it is indeed in play (as you said, basic science), but is the effect significant in the real world? The temp delta between the barrel and the air around the barrel may be so great that the vented gas inside the handguard may be in the noise when this effect is acually measured.

I have the same question about the claimed problems with a DI gun heating the bolt.

It's too bad the world is so hostile to firearms enthusiasts these days because both of these questions would be simple experiments for a high school kid to do for a science fair. ;)

K.L. Davis
08-08-06, 15:44
The 416 uses the same design of piston that is found on the G36 -- it is a very clever design that regulates itself well and vents the gas out the front, not under the handguards.

The SA80 *spit* used the AR18/180 gas system (same as used on the lw design) and it had problems with the venting under the handguard -- the most noted problem was that it would actually blow the top section of the handguard open when firing (it was a hinged "lid" sort of thing). Some 200MPH tape takes care of that though...

...of course an SA80 has never ran long enough to see if the venting location would contribute to heating up :p

SuicideHz
08-08-06, 21:03
I was just about to ask another question that K.L. just answered.

Sure, there is the same amount of heat generated from a fired cartridge in a DI and a piston gun. That does NOT mean the heat that went through the gas tube has to get dumped on another part. The Hot Gases get stopped for the most part at the inner workings of the piston and anything that would have tried to follow them through to the bolt get relieved out the front of the barrel if they don't make it through into the piston system.

CapnCrunch
08-08-06, 21:29
The 416 uses the same design of piston that is found on the G36 -- it is a very clever design that regulates itself well and vents the gas out the front, not under the handguards.

The SA80 *spit* used the AR18/180 gas system (same as used on the lw design) and it had problems with the venting under the handguard -- the most noted problem was that it would actually blow the top section of the handguard open when firing (it was a hinged "lid" sort of thing). Some 200MPH tape takes care of that though...

...of course an SA80 has never ran long enough to see if the venting location would contribute to heating up :p
That SA80 comment cracked me up ;)

The G36 gas system is indeed clever, and it'll be interesting to watch how it pans out in a non-melting platform for the long haul.