Is a Middy THAT much better?


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.Scarecrow.
December 28, 2011, 12:42 PM
I want to first clarify that I am a new guy to this site. So bare with me please, Thank you.

I am planning on getting a DD M4 when I can afford it. I really like the look of a Carbine length rifle. Most Mid-lengths look ugly to me but I am concerned about the differences. I don't want to buy the gun that I really like the looks of then down the road think I wasted my money and should have gotten a Middy. I'm going to use the rifle for fun tactical shooting and home defense. The standard carbine platform when done right seems to do a great job, but some people would tell me otherwise. They make the Middy look like it blows the carbine right outta the water. I've also heard that Mid-lengths recoil less, but I'm not sure. So really my question is, Is the Mid-length SO much better that it is more worth buying one over a carbine?

Once again Thank you.

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taliv
December 28, 2011, 12:48 PM
welcome to THR

just to be clear, you realize that "carbine length" and "mid-length" refers to the gas system only.

both are (typically) 16" barrels. the difference is that one scoots the gas block out about an inch or two further. Regardless of which gas-length you use, you can get the handguards in any length you want from carbine to mid to rifle (~7", 9", 12") (assuming a low-profile gas block)

gearhead
December 28, 2011, 12:49 PM
Assuming you're getting it in 5.56mm, the carbine length recoil is negligible enough that it's not a good reason to avoid it. There is a slight loss in velocity but the ballisticsbytheinch website predicts it to be only on the order of 50-100 fps between a 16" and an 18" barrel. That's within the range of the lot to lot variation in the same type ammo.

Chuck R.
December 28, 2011, 01:36 PM
I donít think so, IF the carbine length is put together properly.

The middy compensates for the short gas system on the carbine, which some say ďover-gassesĒ the system when used with a 16Ē barrel causing early wear and parts breakage. Iíve seen all kinds of reasons for buying one, to include some guys even like them because the front sight and bayonet lug are in the correct distance from the FL so you can mount a standard bayonet.

Iíve owned a Colt LE6920 for a while now, shot it in a couple 500+ round a day classes, and now have about 6K through it and Iíve never experienced a problem.

Chuck

jmorris
December 28, 2011, 01:45 PM
I own them from 7"-24" and can tell you there is no "ideal" just ideal for "X" job.

helotaxi
December 28, 2011, 01:56 PM
Assuming that we're talking mid-length gas vs. carbine length gas on a barrel of the same length...

The mid-length effectively opens the gas port later and has less dwell. The net effect is that pressure has dropped slightly compared to the carbine length system when the gas port is pressurized adn that combined with the longer, higher volume gas tube and lower dwell, means that the bolt carrier isn't sent rearward with as much energy. While the 2nd recoil impulse (the buffer and BCG reaching the rear stop) on the carbine system isn't much, it is less on the mid-length. Not tht big of a deal for a typical shooter, the lower impulse means less upset in the sight picture and quicker follow-up shot.

90% or so of shooters won't care about the difference and a carbine setup works just fine.

henschman
December 28, 2011, 02:20 PM
Well it's like this: the military has them in 2 main configurations -- a 14.5" barreled one with a carbine length gas system, and a 20" barreled one with a rifle-length gas system. They both use the same gas block with the same size gas port, and they both have the same amount of barrel past the gas block, which gives them pretty much the same "dwell time" (which is how long the bullet is in the barrel past the gas block). The longer the dwell time, the more pressure is put on the gas system.

Well, in this realm it is illegal for a common subject to have a barrel shorter than 16" without jumping through some hoops, so when the mfg's started making carbines for sale to civilians, they just slapped the already-available carbine-length gas system on a 16" barrel. That gives it a longer dwell time than the military rifles, which puts more gas pressure on the bolt carrier. This puts a little more wear on the parts, and causes a little greater recoil than a rifle with the original dwell time.

After AR carbines got more popular, the mid-length gas system was invented, which is the proper length to give a 16" barrel the same dwell time as the military issue rifles.

As long as you buy a quality rifle, a carbine gas system on a 16" is fine and can be plenty reliable. But if you want what the original designers determine to be the optimum dwell time for mil-spec ammo, the middy is where it's at. It also gives you a bit longer sight radius if you're using the standard gas block front sight, and a bit longer handguard, which a lot of people like. Of course you can use longer handguards on any AR if you get rid of the original front sight though.

Another option if you want to have the "optimal" dwell time is to get a 14.5" barreled rifle with the carbine gas system, with a permanently-attached flash hider that brings the barrel's overall length over 16". Lots of mfg's are selling uppers/rifles in this configuration now.

My personal preference, and that's all it is by the way, is a 14.5" carbine gas system for a carbine, or a 20" rifle length gas system for a rifle.

minutemen1776
December 28, 2011, 02:50 PM
In a 16-inch barreled AR15, the midlength gas system offers slightly less recoil, as well as slightly less wear on the firearm. Will you notice the difference? Likely not. The midlength also offers a slightly longer sight radius because the front sight is pushed out a bit closer to the muzzle. Will that give you an accuracy advantage? Maybe, but only if you use irons. The midlength also allows the use of a bayonet on a 16-inch carbine, if you're into that. In the end, I think the midlength is objectively better for a 16-inch AR15, but only slightly so. I have two, and I like them. I also like them better than the two carbines I had before them, though the length of the gas system was not my primary reason for changing the ARs I have. All that said, I doubt any benefit from the midlength gas system is enough to choose one is the carbine-length just feels "right" to you. Having a rifle that fits you and feels natural is worth more than all these other factors.

W.E.G.
December 28, 2011, 03:18 PM
Is the Mid-length SO much better that it is more worth buying one over a carbine?

No.

Its just that some "middy" owners are so excited about the fact that their gun is different from the other guns at the range, that they will demand that you acknowledge its superiority.

Most people who buy AR-15's have no idea what they really want, so they just buy something. Then they imagine that the something they just bought could be somewhat different, and they sell themselves on the idea that the different thing will be better. This is how gun safes are filled to overflowing and gun parts end up littering every horizontal space in the man-part of the house.

If your specific NEED (hah! -- like any of us really have one) for a particular configuration dictates a middy, then that's the configuration for you. Otherwise, I expect you to fall in like the rest of us and get different guns until you have multiple times the number of guns than you could possibly utilize in the context of the "regular guy" who has to work and pay bills, all the while paying over a buck just to fire that fancy rifle three shots.

briansmithwins
December 28, 2011, 03:27 PM
I've shot both back to back. I'd rate the original rifle as being the smoothest, the mid-length, with the carbine gas being the harshest.

If I were buying a AR today I'd get another mid-length gas system setup. I don't care much about looks, it's just the mids always worked better for me.

BSW

Captains1911
December 28, 2011, 03:35 PM
Is the middy SO much better.....no. But it does offer advantages over the carbine as others have mentioned. The biggest advantage to me is the extra 2" of rail that allow further forward mounting options and support hand placement. So as the middy isn't SO much better, it does have advantages, so I see no reason to choose the carbine other than if you just like the looks of it better.

henschman
December 28, 2011, 04:09 PM
You asked if it is so much better that it is worth buying over the carbine length gas... If you already had a good carbine model that you like, I would say that it is not worth it to sell it just to buy a midlength. But if you're trying to decide which to buy, I say why not go with the midlength? If the prices are the same either way, there is really no reason not to. Sure the advantages are slight, but there are no disadvantages, so why not?

kwelz
December 28, 2011, 04:28 PM
Would I pick a Middy over a Carbine? Yes?
Would I pass up a good rifle because it was a carbine instead of a Mid length? No.

mokin
December 28, 2011, 04:30 PM
Captains 1911 +1

From what you describe about how you will shoot it, the biggest difference you will probably notice is the extra space to put your forward hand.

taliv
December 28, 2011, 04:52 PM
Its just that some "middy" owners are so excited about the fact that their gun is different from the other guns at the range, that they will demand that you acknowledge its superiority.

Most people who buy AR-15's have no idea what they really want, so they just buy something. Then they imagine that the something they just bought could be somewhat different, and they sell themselves on the idea that the different thing will be better. This is how gun safes are filled to overflowing and gun parts end up littering every horizontal space in the man-part of the house.

If your specific NEED (hah! -- like any of us really have one) for a particular configuration dictates a middy, then that's the configuration for you. Otherwise, I expect you to fall in like the rest of us and get different guns until you have multiple times the number of guns than you could possibly utilize in the context of the "regular guy" who has to work and pay bills, all the while paying over a buck just to fire that fancy rifle three shots.

not this.

Zach S
December 28, 2011, 05:16 PM
Would I pick a Middy over a Carbine? Yes?
Would I pass up a good rifle because it was a carbine instead of a Mid length? No.
My feelings as well.

.Scarecrow.
December 28, 2011, 05:21 PM
Thanks guys. From what I have read, it appears the advantages are Almost negligible. But they are there nonetheless. I guess you could kind of compare it to if I was trying to choose between a Rifle and Carbine. Yeah the rifle has better accuracy, lower recoil, and is less harsh on parts. But I like the way carbines look.

kwelz
December 28, 2011, 05:27 PM
If you want a carbine get this:
http://www.gandrtactical.com/cgi-bin/commerce.cgi?preadd=action&key=6920MP

If you want a Middy get this:
http://www.gandrtactical.com/cgi-bin/commerce.cgi?preadd=action&key=MID-750-LWC

While I am more of a DD and Noveske guy, you can't go wrong with either of those.

mtrmn
December 28, 2011, 06:07 PM
If you get the carbine and DO have problems, you can always install a heavier buffer and/or spring, which is fairly cheap and slows the action slightly and it won't be so "harsh" etc.
I have a couple of Delton carbine builds that are marked 5.56 but they don't like the high pressure loads. Tore the rim off the brass and left it in the chamber, but I could poke one out of the chamber with no effort at all with a cleaning rod. Installed H2 buffers and Wolf extra power springs and they work fine now.

boricua9mm
December 28, 2011, 06:18 PM
I'm one of the few who doesn't notice any difference at all in the recoil impulse between the two gas system lengths. There's theoretical advantages to the midlength that stem from the lower gas port pressure, but they haven't really been proven out at this point in time; it will be a while before that happens. I now am down to owning two midlenghts and no carbine lenghts, but only because I really liked the ways the middies were set up (overall) and I was able to trade my carbine towards something a little more exotic that I really desired. In retrospect, I think a carbine may actually be the best way to go, as the "harsh cycling" that everyone is quick to call out just might be a beneficial attribute in pushing the BCG in dirty conditions (due to environment or high round count).

.Scarecrow.
December 28, 2011, 06:32 PM
That last bit about the rifle in dirty conditions does make some sense. I think I am going to go with a Carbine length. I'll never shoot my gun enough to REALLY notice any problems with it. It's mainly a SHTF (Heaven forbid) gun and to have Tactical shooting for fun. Carbine it is! Yay! I can get the gun I think looks the coolest! haha.

.Scarecrow.
December 28, 2011, 06:33 PM
Well in these cases. Since I am getting a Carbine. What upgrades would you fellas recommend to ensure slightly longer reliability. The rifle I want comes with an H-Buffer, need I change that? What do you guys think.

35 Whelen
December 28, 2011, 06:42 PM
Have you considered a Dissipator? I've been a Rifle Loony since I was a little boy, or 40 some years, but just got my first AR ever, a kit, that I built myself. I wanted a 20", but all Midway had in stock was the Dissipator so I bought it. I'm glad I did. You get the handiness and length of a 16" barrel with the long sight radius as a 20" barrel.
I know they're somewhat ugly and not very popular, but from a practicality standpoint and for someone like me who won't be mounting any sort of optics, I think they're a great compromise.

35W

.Scarecrow.
December 28, 2011, 06:54 PM
I will be mounting Optics, But thank you for your input

taliv
December 28, 2011, 06:58 PM
Harsh cycling and being overgassed is a problem not a benefit. It is one of the reasons they had to go to stronger extractor springs and inserts and heavier buffers.

If you go middy you won't need those fixes for having a suboptimal gas system.

essayons21
December 28, 2011, 07:42 PM
I went with a mid-length gas system on my 16" AR because it was the best option.

16" is as short as my government allows me to have without a special permission slip. I looked at the 14.5" with permanently affixed flash hider, but thought it looked silly. So my options were a carbine length gas system or a mid-length gas system. The mid-length gas system is correct for a 16" barrel, the carbine length gas system is a short cut. Looks were not a factor as I went with a rifle length free float rail. IMO this is the best of all worlds, because I have the shortest possible barrel without paperwork, the correct length gas system, and the longest possible sight radius for iron sights. The only downside is the weight, but this has an added benefit of greatly reducing muzzle rise.

As to W.E.G.'s comments, I own 2 1/2 AR's. One is the aforementioned rifle, another is a AR-10, and the 1/2 is a .22lr upper. My only plans to add to this collection are a lightweight lower to become a dedicated .22lr platform. If you know what you want, buy it, and be happy.

P.B.Walsh
December 28, 2011, 07:45 PM
Middys can use bayonets!! :evil:

Matthew Courtney
December 28, 2011, 07:57 PM
Harsh cycling and being overgassed is a problem not a benefit. It is one of the reasons they had to go to stronger extractor springs and inserts and heavier buffers.

If you go middy you won't need those fixes for having a suboptimal gas system.
Suboptimal gas system- is that the best gas system for a U-boat?

2WheelsGood
December 28, 2011, 08:08 PM
If you go middy you won't need those fixes for having a suboptimal gas system.

Serious question coming from someone new to ARs... if it is suboptimal, why do they make them? I mean, is there any advantage at all to the carbine length? It seems like there are an awful lot of them out there, so if there are no advantages, why bother making them? I assume the OP is rare in that he prefers it just because it looks cool.

By the way, being new to ARs myself, this is the best thread I've read in a long time.

jmorris
December 28, 2011, 08:43 PM
What upgrades would you fellas recommend to ensure slightly longer reliability.

Good ammo and mags. They will make a bigger difference than the gas system.

taliv
December 28, 2011, 08:57 PM
honestly, i don't know 2wheels, but i suspect as was mentioned before, it was an attempt to be as close to the M4 as possible, which is basically everything except the full-auto trigger and the extra 1.5" of barrel. they were probably cheaper to make that way. i really don't know, but for example, they might be able to use the same machine/jig to drill the hole in the 16" bbl as they do the 14.5" military bbl.

remember that until maybe even this year, almost all midlengths were made by small companies. in relatively tiny quantities. now that FN and DD are flooding the market with quality low-cost barrels, i'd expect a lot of things to change. heck, i even saw a colt 6920 today that came from the factory with magpul MOE stock, grip and handguard. that's would have been almost unimaginable just a few years back

also, knights and some others are using an "intermediate" length. lots of people are trying to find "optimal".

helotaxi
December 29, 2011, 12:16 AM
They probably didn't realize that it was an issue until they realized it was an issue. The gas tubes and handguards were already in production for the carbine, so it appeared initially that adding 1.5" to the barrel was all that was needed until they tried it out and found out that it was temperamental. At that point someone who actually understood how the whole thing worked looked at it and said "Hey...mid-length...dwell...etc..." and they started making parts specifically for the civilian market.

Hacker15E
December 29, 2011, 08:14 AM
The "value" of a midlength in terms of the mechanics of "overgassing", etc, is wildly overblown. People are

The vast majority of shooters will never put enough rounds down the pipe for it to even be an issue.

It's certainly a smart innovation for a 16" barrel, but it's not the second-coming like many seem to believe.

If the cost is all the same, then this is how I'd buy:

Less than 16" barrel: carbine gas
16" barrel: midlength gas
greater than 16" barrel: rifle gas

boricua9mm
December 29, 2011, 09:42 AM
The notion that, automatically, carbine length = overgassed is a flawed argument. There's much more at play then how far away the gas port is. The size of the gas port diameter itself, the mass that it must push, and the ammo providing said gas are all equally important variables. In the past I've owned middle-of-the-road carbines with standard carbine springs, CAR buffers and semi-auto carriers that ran 100% for a long time using both commercial .223 and military grade 5.56 ammo. These rifles were shot considerably, not 40 rounds at a time. In my experiences, it's not that an extractor spring insert and an H-Buffer (or heavier) are required fixes with a properly drilled gas port, it's that they are good insurance policies.

In the past, carbine manufacturers had to contend with the fact that there's a lot of cheapskates out there who will spend $1200+ on a carbine and then be on an eternal quest to find and shoot the cheapest, most questionable ammo out there. As a result, the gas ports were drilled larger and more gas was introduced into the whole system. That's the "overgassing" worth discussing. When we move on to middy users, we find that they are still using H-buffers and extractor spring upgrades for the added insurance; then again, they generally aren't trying to run the gauntlet with underpowered garbage ammo.

It is worth noting that when carbine instructors and subject matter experts such as Larry Vickers spec out a carbine (or recommends one for that matter), it uses a carbine length gas system. Perhaps we're not completely astray in our opinions that the advantages of the middy aren't all that they're cracked up to be.

Why do carbine length gas ARs continue to dominate? It has been proven that it works through decades of use. People continue to buy them. They continue to work.

.Scarecrow.
December 29, 2011, 10:06 AM
Yeah I get what your saying Taliv it's just I can't get over how Every middy I see is ugly as hell.

boricua9mm
December 29, 2011, 10:27 AM
Eye of the Beholder and such; some folks think that 16" barrels look stupid with a carbine length handguard on them. I don't think it looks silly at all, but I also like the look and utility of a rifle length rail on a 14.5 or 16" barrel.

One thing that I say that midlenghts do offer in a measurable way is that the gas port location being further out slows down the gas port erosion, which is genuinely a good thing.

They also tend to make people gravitate towards more expensive rail systems, which is good for the US gun industry. :D

.Scarecrow.
December 29, 2011, 12:30 PM
The notion that, automatically, carbine length = overgassed is a flawed argument. There's much more at play then how far away the gas port is. The size of the gas port diameter itself, the mass that it must push, and the ammo providing said gas are all equally important variables. In the past I've owned middle-of-the-road carbines with standard carbine springs, CAR buffers and semi-auto carriers that ran 100% for a long time using both commercial .223 and military grade 5.56 ammo. These rifles were shot considerably, not 40 rounds at a time. In my experiences, it's not that an extractor spring insert and an H-Buffer (or heavier) are required fixes with a properly drilled gas port, it's that they are good insurance policies.

In the past, carbine manufacturers had to contend with the fact that there's a lot of cheapskates out there who will spend $1200+ on a carbine and then be on an eternal quest to find and shoot the cheapest, most questionable ammo out there. As a result, the gas ports were drilled larger and more gas was introduced into the whole system. That's the "overgassing" worth discussing. When we move on to middy users, we find that they are still using H-buffers and extractor spring upgrades for the added insurance; then again, they generally aren't trying to run the gauntlet with underpowered garbage ammo.

It is worth noting that when carbine instructors and subject matter experts such as Larry Vickers spec out a carbine (or recommends one for that matter), it uses a carbine length gas system. Perhaps we're not completely astray in our opinions that the advantages of the middy aren't all that they're cracked up to be.

Why do carbine length gas ARs continue to dominate? It has been proven that it works through decades of use. People continue to buy them. They continue to work.
I liked that a lot, it gave me much more assurance. It seems like maybe a simple solution might be to make the Gas Port a smaller diameter. It might not be able to Run cheap ammo, but I'm going to feed my rifle quality ammo just like I feed my Bearded Dragon quality nutritious food. Life's too short to shoot cheap ammo if you ask me.

helotaxi
December 29, 2011, 01:06 PM
The answer is to make the gas port the "correct" diameter.

The whole thing has to be looked at as a system. If one part of the system isn't correct, others have to able to compensate for it or the whole thing fails.

.Scarecrow.
December 29, 2011, 03:30 PM
The answer is to make the gas port the "correct" diameter.

The whole thing has to be looked at as a system. If one part of the system isn't correct, others have to able to compensate for it or the whole thing fails.
A Manufacturer should start making barrels like that. Would solve the parts wear problem (As minor as it is) and cause Crappy Ammunition brands to step up their game.

SpeedAKL
December 29, 2011, 04:49 PM
Other people already covered the technical reasons for why a midlength gas system is superior in a 16-in barrel. Practically speaking, the gun's build quality will affect reliability far more than having a carbine- or midlength gas system on your 16-inch barrel. Plenty of quality 16-in carbines have been run hard with zero issues. If you plan to do "tactical shooting" (classes or competition) involving lots of rounds downrange, get a gun that is first and foremost built to high quality standards.

All else equal I prefer the midlength because I notice slightly gentler recoil and slighter better balance when shooting it. These are just personal observations though.

kscharlie
December 29, 2011, 07:30 PM
I don't understand why you think a mid-length is ugly. Both the carbine gas system and the mid-length gas system are built on 16" barrels (assuming that is the length of barrel you want). The only difference between them is the front sight/gas block being moved out a bit, and a slightly longer handguard. Otherwise, they are the same gun.

I bought a stripped lower, a decent lower parts kit, and put together the lower. I then bought a complete upper from BCM and got one with a mid-length gas system. I enjoy the heck out of the gun. If it were a carbine length gas-system, I would still enjoy the heck out it. They are a fun gun to shoot, regardless of configuration. Good luck on your decision.

http://i839.photobucket.com/albums/zz320/kscharlie/ARandP250sc/DSC02728a.jpg

.Scarecrow.
December 29, 2011, 07:33 PM
Other people already covered the technical reasons for why a midlength gas system is superior in a 16-in barrel. Practically speaking, the gun's build quality will affect reliability far more than having a carbine- or midlength gas system on your 16-inch barrel. Plenty of quality 16-in carbines have been run hard with zero issues. If you plan to do "tactical shooting" (classes or competition) involving lots of rounds downrange, get a gun that is first and foremost built to high quality standards.

All else equal I prefer the midlength because I notice slightly gentler recoil and slighter better balance when shooting it. These are just personal observations though.
I have heard Great things about Daniel Defense and people seem to say they make top notch rifles. I fired my buddies extremely stock Bushy that had no muzzle device and the recoil was about twice that of a .22LR on my shoulder. I think with the proper fore-end grip and muzzle device, I can make it even less. So the recoil is not a factor to me.

Zerodefect
December 29, 2011, 07:56 PM
No.

The Colt 6920 has perfect ejection patterns. I think it has a smaller port. Carbine gas can take advantage of more dwell, but have less pressure and flow because of a smaller port. This can be a reliable compromise if you shoot weak or dirty Wolf type ammo.

If you want to soften your recoil impluse like a middy, just send your barrel to Adco and tell them to cut it down to 14.5". Then the length from port to end of the barel is once again very close to optimal. (You'll also need a longer flash hider pinned/welded to maintain the regular 16" legality, I recommend the PWS 556.) I plan on having my 6920 cut down to 14.5 very soon.

Where it gets real fun, is under gassing. IE: 14.5" carbines with a middy gas system, and 18" rifles with rifle gas systems. Very nice soft shooters, especially the 18".

MistWolf
December 30, 2011, 01:07 AM
Middies Have Less Recoil Er, no. The cartridge puts out the same amount of recoil energy whether it fired in a middie or carbine. What's different is the recoil impulse.

Dwell Time "I don't think that word means what you think it means." Seriously. Dwell time is measured in fraction of a millisecond. As in tenths of a millisecond. A millisecond is one one thousandths (1/1000) of a second. How much extra pressure can you build up in in less than a millisecond? Especially when you take into account the bullet has cleared the muzzle by several feet before the carrier even thinks about beginning to move. What's the real difference between a 16 inch carbine and a 16 inch middie? Volume. Not much when it's only an extra inch and a half of 22 caliber bore but it's filled with roughly 15,000 psi of compressed gas. The extra volume will take more time to exit the muzzle after the bullet uncorks the barrel. That's why suppressors have extra blow back.

How Did They Come Up With the Carbine Length? When the M4 was first being introduced, I read a technical article about the development. They pretty much shortened the the barrel as much as they could with the correct distance from the gas bloc to the muzzle to fix a bayonet while maintaining reliable functioning. The barrel length they reached was 14 inches. They added a half inch to that for insurance and called it a day.

How They Developed The Middy Armalite first developed the middie on a 16 inch barrel so the gas block would be at the right distance to mount a bayonet. Nothing more fancy than that. After that, the Marketing Boys were off & running touting the real & imagine advantages of the middie.

Personally, I like the middie better as it I think it makes more sense. But both work. I bought a middie because of personal preference. There is no reason why a shooter couldn't choose a carbine for the same

Bartholomew Roberts
December 30, 2011, 09:01 AM
The carbine gas system was basically developed for the Colt Commando/XM177 series of weapons which had a 10.5" barrel. They soon discovered dwell time problems and added a moderator/flash hider that increased backpressure and dwell time enough to help with function; but that still didn't solve the issues so they went to the XM177E2, which had an 11.5" barrel, and worked more reliably but continued to be less reliable than the M16.

Somewhere along the line, Colt extended the barrel out to 14.5" (which happens to give a dwell time very similar to the 20" rifle) and lost the special moderator/flash hider, while keeping the gas system from the Commando.

So in short, I suspect the reason we have a carbine length gas system is because that made sense when they built the first 10.5" guns and they just continued to use it in future developments.

As far as the difference between it and a middy, there is a difference there but not a dramatic one. I think a well built carbine system will run as well as a well-built middy for the most part. There is a much better understanding of the M16 family of weapons these days. The Mk18 CQBR has a 10.3" barrel (0.2" shorter than the original Commando) and no moderator and it has been judged more reliable than the HK416 in some tests. I think the major issue is getting the right gas port size to match the length/dwell time and then the proper buffer/spring and preventive maintenance.

.Scarecrow.
December 30, 2011, 01:53 PM
No.

The Colt 6920 has perfect ejection patterns. I think it has a smaller port. Carbine gas can take advantage of more dwell, but have less pressure and flow because of a smaller port. This can be a reliable compromise if you shoot weak or dirty Wolf type ammo.

If you want to soften your recoil impluse like a middy, just send your barrel to Adco and tell them to cut it down to 14.5". Then the length from port to end of the barel is once again very close to optimal. (You'll also need a longer flash hider pinned/welded to maintain the regular 16" legality, I recommend the PWS 556.) I plan on having my 6920 cut down to 14.5 very soon.

Where it gets real fun, is under gassing. IE: 14.5" carbines with a middy gas system, and 18" rifles with rifle gas systems. Very nice soft shooters, especially the 18".
I saw the Daniel Defense Torture test video, Would a Colt be able to do the same?

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