View Full Version : New guy with a question
Rocknoggin
06-17-19, 10:13
Hi, just joined the forum and I have a question. A friend recently bought a Colt M4 Carbine and let me try it, and now I want one. It was the first time I'd shot any type of AR. Last 'black rifle' I shot was an M16A2 when I was in the Army (got out 25 years ago). I like my friend's M4, it functions flawlessly. But the M4 Trooper caught my eye. I started doing some digging and I'm running into lots of terminology I've never heard of. What's the difference between a mid-length gas system and carbine gassed? And which does these two have? I heard someone say mid-length is better but I don't know why.
556BlackRifle
06-17-19, 10:32
Welcome to M4C. If you do a forum search you can find a lot of good info on questions that have been asked and answered over the years. This thread should get you started. Good luck.
https://www.m4carbine.net/showthread.php?51748-mid-length-gas-system-vs-carbine-length
556BlackRifle
06-17-19, 10:32
Double Tap.
Believe they both have a carbine gas system. The difference is where the gas port/gas block is placed. So on the carbine gas system the distance between the bolt carrier and the gas port is 7", on the mid 9". One of the ideas for a mid was to soften the felt recoil a bit.
Rocknoggin
06-17-19, 10:48
One of the ideas for a mid was to soften the felt recoil a bit.
That's it? Makes no difference to reliability?
That's it? Makes no difference to reliability?
I don't really remember all the technical reasons for it. Someone with more knowledge will have to answer that. An increase in reliability could be one reason, but in day to day use that's more theoretical IMO.
Eurodriver
06-17-19, 11:15
I started going to church.
That's it? Makes no difference to reliability?
The middy gas system done correctly is slightly more reliable than the carbine gas system when used in conjunction with 14.5 & 16 inch barrels. The middy taps gas from the barrel a couple of inches further from the chamber where the pressure is a bit lower. The middy is a little more forgiving. But there it's nothing wrong with the carbine gas system when done right.
I've shot Colts with 16" barrels with carbine length gas systems and they work fine, better than some of the other brand ARs with middy gas systems. With the carbine gas system, I prefer the 14.5 inch barrel over the 16 inch barrel, but to be honest, that's to satisfy my CDO more than for any reliability gains. Any of the Colt carbine configurations, 6920, Trooper, CCU or lightweight, will serve you just fine. Pick what you like and get to shooting!
Doesn't the mid length charge the gas system a tiny bit slower easing ejection?
Rocknoggin: as others have said, you can learn a lot by searching the forum (scroll to the top of the page and search button is on the right). As an example, I searched mid-length versus carbine length and found this thread:
https://www.m4carbine.net/showthread.php?206740-NSWC-testing-on-gas-systems-CARBINE-VS-MID-LENGTH
and then I found these listed in a thread:
https://www.m4carbine.net/showthread.php?t=51187
https://www.m4carbine.net/showthread.php?t=51542
https://www.m4carbine.net/showthread.php?t=51421
https://www.m4carbine.net/showthread.php?t=35517
https://www.m4carbine.net/showthread.php?t=2303
https://www.m4carbine.net/showthread.php?t=39400
https://www.m4carbine.net/showthread.php?t=39367
This place can take you down the rabbit hole pretty quickly. I come here for a scroll through, and end up for a couple hours, which is okay, I'm retired, so it's not like I'm playing on the puter at work like some of these guys are :)
I try to buy mid-lengths whenever I can, IMO, they shoot smoother (a subjective impression). If you really want to go down the rabbit hole, read about the A5 system:
https://www.m4carbine.net/showthread.php?190748-The-Vltor-A5-System
With the A5 you can pretty much make your mid-length shoot like a tuned rifle gas system, once again my subjective opinion.
Anyways, have fun on the forum.
BTW, have you considered the Colt CCU, it has a mid-length system:
https://www.budsgunshop.com/catalog/product_info.php/products_id/719014177/Firearms/Rifles/Colt/Colt+Combat+Unit+M4+5.56+16in+30+1
https://www.tombstonetactical.com/catalog/colt/le6960-ccu-le6960-talo-special-edition-ar-15-rifle-5-56mm-16in-30rd/
You might have to look to find one in stock. Or you could 'build' you own:
https://www.brownells.com/rifle-parts/receiver-parts/receivers/upper-receivers/ar-15-le6960-ccu-upper-receiver-5-56-m-lok-prod120469.aspx
https://charliescustomclones.com/colt-m4-lower-receiver-complete-2018-production/
https://www.armsunlimited.com/Colt-M16-M4-AR15-Charging-Handle-Assembly-p/sp62290.htm
https://www.armsunlimited.com/Colt-M16-AR15-Complete-Bolt-Carrier-Group-Assembly-p/sp64028.htm
and it would be all Colt.
everready73
06-17-19, 13:16
Doesn't the mid length charge the gas system a tiny bit slower easing ejection?
You have increased dwell time which should ease ejection and overall parts wear on the rifle from my understanding
Rifleman_04
06-17-19, 13:39
Don't waste too much time worrying about gas systems, incorrect understandings of dwell times, gas port sizes, tuning and such forum silliness. Pick a quality gun(either Colt you spoke of are good) and just shoot it.
Don't waste too much time worrying about gas systems, incorrect understandings of dwell times, gas port sizes, tuning and such forum silliness. Pick a quality gun(either Colt you spoke of are good) and just shoot it.
Silliness? I dont think so. Knowing how my rifle works and at least some of the specs is required IMO.
I joined this forum to learn about serious “fighting quality” rifles as well. Got plenty of good advice and spent many months researching threads before I bought anything. Early on one word of advice was “if you don’t want to spend time researching just buy a Colt 6920”. Well I ended up with that in the end anyway but I’m glad I spent the time to learn and I recommend you do the same. There are WAY more quality options out there now.
That said, if I was looking for my first quality fighting rifle today, I would strongly consider the Colt CCU as some others mentioned. It has got practically everything you need and nothing you don’t. What Colt should have been making 10 years ago.
Rifleman_04
06-17-19, 18:04
Silliness? I dont think so. Knowing how my rifle works and at least some of the specs is required IMO.
Factory specs? Sure.
I was talking specifically about the silly crap spouted in these threads that generally devolve into a debates with a bunch of internet operators claiming every gun needs to be tuned into barely functioning gamer guns with minimum sized gas ports and and 80 different buffer and action spring combinations.
Shoot. The. Gun.
Rocknoggin
06-17-19, 18:44
I tried to look up the CCU but the page has been removed from Colt's website.
Does the Trooper have the same barrel as the 6920? Or is it the pencil barrel?
You will probably be able to locate the LE6960 specs you're looking for by viewing the product pages of resellers, or by asking here. I've only had the CCU upper for about a month, but like it so far. I plan to take it and the Trooper to an indoor range sometime this week for a comparison.
The LE6920-R does use the same barrel as a standard LE6920. The pinned A2 FSB is cut down and shaved to fit under the Centurion-sourced handguard.
midlength hype is just like the .40cal hype
midlength hype is just like the 9mm hype
FIFY...
Hi, just joined the forum and I have a question. A friend recently bought a Colt M4 Carbine and let me try it, and now I want one. It was the first time I'd shot any type of AR. Last 'black rifle' I shot was an M16A2 when I was in the Army (got out 25 years ago). I like my friend's M4, it functions flawlessly. But the M4 Trooper caught my eye. I started doing some digging and I'm running into lots of terminology I've never heard of. What's the difference between a mid-length gas system and carbine gassed? And which does these two have? I heard someone say mid-length is better but I don't know why.
M4 and trooper both have carbine gas.
Midlength gas for a 16” barrel may be better theorietically, but there are a lot of variables. If you buy from a quality manufacturer like colt, its safe to assume everything is made correctly for the system it is built with.
Since you are new- reliability should be your only concern. Get one and practice with it.
Edit: carbine gas has the gas block 7” down the barrel, midlength has the gas block 9” down the barrel (from the receiver end).
FIFY...
not really. just like the 40cal was an in-between solution for the 9mm and 45cal. the mid-length is something they came up with for range and compactness.
not really. just like the 40cal was an in-between solution for the 9mm and 45cal. the mid-length is something they came up with for range and compactness.
I'll just leave these here:
http://the-eye.eu/public/murdercube.com/Gunsmithing/ArmaLite_Technotes/Effects%20of%20Heat%20and%20Barrel%20Design%20on%20M16%20Functioning%20-%20tnote48.htm
http://soldiersystems.net/2018/05/14/nswc-crane-carbine-mid-length-gas-system-testing-shows-increased-performance/
That said, if I was looking for my first quality fighting rifle today, I would strongly consider the Colt CCU as some others mentioned. It has got practically everything you need and nothing you don’t. What Colt should have been making 15 years ago.
FTFY.
You will probably be able to locate the LE6960 specs you're looking for by viewing the product pages of resellers, or by asking here. I've only had the CCU upper for about a month, but like it so far. I plan to take it and the Trooper to an indoor range sometime this week for a comparison.
I'll save you the trouble: The 6960 is softer shooting, better balanced, a hair lighter with better furniture (IMO).
I'll just leave these here:
http://the-eye.eu/public/murdercube.com/Gunsmithing/ArmaLite_Technotes/Effects%20of%20Heat%20and%20Barrel%20Design%20on%20M16%20Functioning%20-%20tnote48.htm
http://soldiersystems.net/2018/05/14/nswc-crane-carbine-mid-length-gas-system-testing-shows-increased-performance/
Thank you. I've been looking for that Armalite Tech Note for a while...
TLDR: Carbine gas was a poor engineering choice that was largely a carryover from the early shorty M16s and then largely perpetuated because "muh mil-spec". A couple decades of GWOT and civilian interest has mitigated quite a lot of the issues (correcting gas drive via port size or do-dads, buffer/spring kits, extractor upgrade kits, enhanced bolts and carriers) but there is zero reason not to buy a mid or intermediate length over carbine gas system in 2019 for 14.5+ barrels.
RVTMaverick
06-18-19, 14:11
https://www.youtube.com/watch?v=f-GFrPBatEY
Rocknoggin
06-18-19, 19:17
I'm not sure what's up with the church comment or the fishing video, but thanks for the other replies.
titsonritz
06-19-19, 00:05
There's nothing wrong with a 6920, they are solid guns, but I don't ever see myself buying another carbine gas or buffer system on a 14.5" or 16" barrel carbine. I've moved to the mid gas and A5 buffer system, when properly built it is a better setup.
RVTMaverick
06-19-19, 06:42
LMAO.... Sorry Rocknoggin, It was supposed to be a video of "Sootch and his review Savage's Awesome MSR15"... I'll try and pull it back up, I did a copy and paste... SO I have NO idea WTHeck happened?
I hope this works this time.... Which by the way is why My Title to you IS: YO OP! My .02 for Serious Consideration
https://www.youtube.com/watch?v=1WWUjw9AQ-U
OK... It took this time!;)
I'm not sure what's up with the church comment or the fishing video, but thanks for the other replies.
Rocknoggin
06-23-19, 15:46
Well, the Trooper is a no go. Colt is out of stock and every place I've tried is the same. No distributors have any in stock and no one can order one until Colt makes another batch. So I ordered a 6940 instead. Should be here within a week.
I think the 6920-R Trooper was a relatively limited run to get rid of OEM2 6920 barrels (shaved FSB) but I hope they make them again.
At the price point of $700-800, it crushed the other options out there like the CCU which went for $1200-ish with middie gas, Magpul furniture and a better Centurion rail (extra screw and integral QDs).
Yeah, middie gas is 'better', but for the price the 6920-R Trooper was a great rifle. I have one and it's rapidly become a favorite of mine.
If you are jonesing for a CCU, Brownells sells the upper for $599 and with 10% off sales, you can get it for $540 (no CH or BCG).
Well, the Trooper is a no go. Colt is out of stock and every place I've tried is the same. No distributors have any in stock and no one can order one until Colt makes another batch. So I ordered a 6940 instead. Should be here within a week.
I had a 6940 and it was a laser beam. You shall love that gun, well done. It was my first black rifle. Excellent purchase.
PB
Well, the Trooper is a no go. Colt is out of stock and every place I've tried is the same. No distributors have any in stock and no one can order one until Colt makes another batch. So I ordered a 6940 instead. Should be here within a week.Nothing wrong with a 6940, but you're married to that 7" monolithic rail. The 6920 OEM #, 6920 EPR or the 6960 would have been more versatile choices IMO.
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Rocknoggin
06-23-19, 22:01
Nothing wrong with a 6940, but you're married to that 7" monolithic rail. The 6920 OEM #, 6920 EPR or the 6960 would have been more versatile choices IMO.
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I wanted the rail. That's why I was looking for a Trooper.
I wanted the rail. That's why I was looking for a Trooper.Are we taking about the same thing? The Trooper LE6920-R has a 13" free floated M-LOK handguard from Centurian. The LE6940 has a monolithic upper receiver with 7" picatinny rail. So sure, they both have "rails" but one is arguably too short for proper hand placement and is integrated into the receiver... Unless you meant to type LE6960?
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Rocknoggin
06-23-19, 22:23
Are we taking about the same thing? The Trooper LE6920-R has a 13" free floated M-LOK handguard from Centurian. The LE6940 has a monolithic upper receiver with 7" picatinny rail. So sure, they both have "rails" but one is arguably too short for proper hand placement and is integrated into the receiver... Unless you meant to type LE6960?
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Yes, that's what I meant. I know the difference. The 13" rail would work but I don't need one that long.
A friend recently bought a Colt M4 Carbine and let me try it, and now I want one. It was the first time I'd shot any type of AR. Last 'black rifle' I shot was an M16A2 when I was in the Army (got out 25 years ago). I like my friend's M4, it functions flawlessly. But the M4 Trooper caught my eye. I started doing some digging and I'm running into lots of terminology I've never heard of. What's the difference between a mid-length gas system and carbine gassed? And which does these two have? I heard someone say mid-length is better but I don't know why.
I wanted the rail. That's why I was looking for a Trooper.
The 13" rail would work but I don't need one that long.
I'm not the one that usually does this, but, respectfully, you don't know what you don't know. If you've never heard that phrase before, think about it.
Unless you are goinf to spend your time shooting with your support hand grasping the mag well, or holding a VFG like a pornstar, a carbine length rail is not going to be long enough if you put any ancillary equipment on it such as a light.
If you look around the world of real shooters, whether you believe that is our SOF soldiers, 3-gun shooters, or just top level trainers, very few of them, if any, are running carbine length handguards/rails on 14.5 or 16 inch rifles.
The primary reason for that is that the longer handguards offer more to the shooter in terms of ergonomics, regardless of how you shoot.
Since you probably can't undo what you've done, even if you wanted to, I honestly don'y know why I've posted.
Enjoy your new rifle, I'm afraid if you shoot it much and evolve as a shooter, you will be looking for a new upper soon.
Rocknoggin
06-23-19, 23:05
very few of them, if any, are running carbine length handguards/rails on 14.5 or 16 inch rifles.
Then why does everyone recommend a 6920 as a first rifle?
Then why does everyone recommend a 6920 as a first rifle?Because it's a known quantity that works and because you can always put on a low profile gas block and the handguard style and length of your choice, not so with the 6940; you're stuck with the short rail until you buy a new upper receiver.
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Rocknoggin
06-23-19, 23:38
Because it's a known quantity that works and because you can always put on a low profile gas block and the handguard style and length of your choice, not so with the 6940; you're stuck with the short rail until you buy a new upper receiver.
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Okay, that makes sense. But I don't see that being an issue at this point because I liked the way my friend's 6920 felt with the short handguard when I was shooting it. That's why I said a longer one would work but wasn't necessary.
But I can see the other points being made here. If I do change my mind about that later, I can deal with it. I'm not averse to making changes as necessary. Costs some extra money to do it? Yeah, but that's the only downside I'm seeing. I've had to spend money to make changes with plenty of things before (guns, cars, electronics, etc). That's life. For now I like what I see and I'll just roll with it until/if I change my mind. If that happens, then I'll make the necessary changes. I appreciate the constructive criticism, I'll keep it in mind as I go.
Fair enough. It may not be ideal, but it'll still work. If you're going to slow fire rested from a bench it probably doesn't matter anyway.
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I would think the other way: the more you train, the more you will realize most “accessories” for the AR-15 are just there to make money. There isn’t a lot you can’t do with a stock 6920, sling, light, and optic.
I spent several years being best friends with a M4A1 with KAC 7” handguard. That was the one thing I wanted most to change about the weapon. I was elated to find that handguards were growing in length.
It matters a lot less if you don’t use a light and PEQ, I suppose. Put on some slim covers like the Magpul or Ergo ladders and rock on.
Then why does everyone recommend a 6920 as a first rifle?
I believe largely because this is 'M4 CARBINE,net.'
It is true the 6920 is a good starter rifle, especially if you are going to use irons.
Generally folks who come onto the forum asking 'what should I get? are new to the AR and the 6920 will serve them well. They likely won't develop into weekly or daily shooters, instead becoming the typical 'shot a hundred rounds when I bought it, and 20 rounds each year, unless I forget' type of shooter. A 6920 will serve them well, it is reliable, and will give them solid serviceability throughout the years.
If someone develops as a shooter, more than likely that 6920 will either: 1) maintain an honored space in the safe as the first rifle I bought; 2) be traded/sold for something different; 3) have the upper converted to a free-float rail and, in most cases rebarreled.
If you look back through the archives of this forum (search just buy a 6920) you will find that folks have submitted the rifle to numerous trials and tribulations to prove their point. From their perspective. From my perspective, leaving a rifle out in bad weather, running over it with a truck, or shooting it several thousand rounds with out cleaning, have very little to do with convincing me the 6920 is the Rifle.
From my perspective there are several things I would like to know about a shooter before making a blanket recommendation:
1) What is the intended use? Strictly home defense? Probably a solid choice. Prairie dog blasting or ringing metal at 400 to 600 yards? Probably not optimal, I would steer you to something else. You get my drift.
2) Age. At some point everyone's vision begins to deteriorate, normally a condition called presbyopia it is the normal loss of ability to focus on near objects. It often makes use of standard iron sights on pistols and rifles with any degree of precision difficult, if not impossible. Looking through a reduced rear aperture may mitigate the condition, but is generally something competitive service rifle shooters utilize. Likewise, presbyopia causes the reddots to flair/blossom. This reduces accuracy. Is it good enough for HD distances - probably, not certainly.
So if you are approaching 40, or wear reading glasses or bifocals, I'd recommend a scope, generally a LPVO (low power variable optic), or, an etched reticle optic as the answer.
IMO, a front sight intruding into the optic is an unnecessary intrusion when using optics. There have been great strides made in the design and manufacturing of optics, reasonably priced one are reliable. As a result, many, myself included do not run BUIS (back up iron sights) on weapons with optics. This eliminates an unmodified 6920 from the list of preferred first rifles.
Experience, The learning curve is easier with an optic than it is with iron sights. If you aren't already comfortable with aperture iron sights, I'd steer you to the optic. Once again moving the 6920 down the list of preferred starter rifles. It is also easier IMO to learn to shoot rifles if you can 'spread out' a little with your support hand. Something the short carbine rails aren't known for.
I hope my explanation makes sense to you. I have listed why I feel that the 692 is not the go to first rifle for all folks.
BTW, your 6940, hits the optics box with it's folding front sight and Magpul BUIS - you should be able to use any optic configuration you want, within reason. As I mentioned earlier, if you are putting a light and a laser designator on the handguard, that carbine handguard is going to get crowded, fast.
Rocknoggin
06-24-19, 18:50
I believe largely because this is 'M4 CARBINE,net.'
I meant generally speaking, not just here. But thanks for all the info, I'm making a note of everything.
Then why does everyone recommend a 6920 as a first rifle?
Because the rifle is a known quantity and it works. The 6920 gives the shooter, whether they are a first time AR owner or one with years of experience, a solid foundation to build on. It's easier to recommend a rifle that has all the basics right than to give a grocery list of things to look for when buying something like a RRA, Bushy, PSA or other similar brand.
You did right deciding what rifle you wanted and getting it. Now, you can get to shooting instead of spending weeks and months agonizing over the details before buying anything. It's possible you'll like the monolithic upper just fine. It's also possible that you'll decide you want something else. But you'll find out by actually shooting the rifle. You can't buy experience. You can't internet experience, either.
When I first got started modifying and building ARs, I decided I wanted free float tubes on everything. However, free float tubes can be expensive. One build was delayed because I couldn't afford the free float tube I wanted. Finally, I just bought a MOE handguard and got to shooting. I've been shooting that build for years and it still doesn't have a free float tube. I learned more getting the drop in handguards and to shooting than if I waited until I could afford a free float tube.
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