Barrel length

[porterdavid98]

Anybody have an idea how 16 inches became the most common length for AR weapons? Why not 18 inches?



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[VIPER 237]

It’s the shortest legal length. I think if there was no NFA we would see 11.5 and 14.5 as the norm.

[alamo5000]

I agree with Viper. It's the law.

I will defer on this point because I have zero military experience but rather add an additional question into the mix... for those that have been in the military isn't a 14.5 the standard issue? Isn't the M4 a standard 14.5 inch length?

I would speculate that 14.5" is probably the best all around length for 5.56 in regards to terminal ballistics, reliability, wear on guns, etc.

How they came up with a random number of 16" is beyond me. That was made by politicians not gun people.

[fledge]

Politicians had 1934 mob-owned firearms in mind when they wrote the 16” rule.

[alamo5000]

Politicians has 1934 mob-owned firearms in mind when they wrote the 16” rule.

I had that in mind too. That law definitely pre-dates any M16 or AR platform.

[UWone77]

Anybody have an idea how 16 inches became the most common length for AR weapons? Why not 18 inches?



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Other than the Law/NFA that's been mentioned, I think 18" and above are just a little too long for carbine work.

[Former11B]

Other than the Law/NFA that's been mentioned, I think 18" and above are just a little too long for carbine work.

Absolutely

I’m probably going to build a 22” AR of some sort in a wildcat (224Valkyrie is what I’m planning thus far) but beyond that, I got rid of my 18” and 24” .223 stuff. 16” rifles with a suppressor is bad enough; my 24” rifle with my direct thread can was insanely quiet but it was ridiculously long.

A pinned 14.5” rifle with a quick attach can (like the Griffin M4SD-II or NT4) would be pretty sweet, otherwise I’m rocking the 10.5 and 16 inchers

[BoilerUp]

Remember that until the mid- to late-1990's a typical "AR-15" in civilian hands was modeled after the M-16 with a 20" barrel. When the Army started cutting over to the M4, the M-forgeries started appearing. And, as mentioned, a 14.5" barrel requires a tax stamp so the civilian market settled on the 16" as sold by Colt the small market for "clones" like Bushmaster.

Also, the reason the Army was comfortable going to the 14.5" barrel was that the 1:7 twist with 62 gr bullets was giving the required ballistic performance. The 20" barrel wasn't really needed for the standard grunt. DMRs stuck with 20" and SPRs went with 18" where the extra velocity served a purpose.

These days, the only reason to have more than 16" is if you really value a little bit of extra velocity because you're pushing the performance of the round. The majority of civilian shooters aren't.

[gatordev]

These days, the only reason to have more than 16" is if you really value a little bit of extra velocity because you're pushing the performance of the round. The majority of civilian shooters aren't.

And with the IAR coming online, a large portion of the military isn't either.

[Stickman]

We should all go back to 20" AR's

[JMJ]

We should all go back to 20" AR's

@Stickman just out of curiosity are you joking or serious and if serious why do you think that?



I've got a 16" Govt profile, an 18" bull barrel and a 20" Hbar profile 5.56. Of the 3 my 20" is my favorite and has become a dedicated hunting rig for short range deer, hogs and predators. The 16" Govt profile is typically what I carry when hiking or stalk hunting and the 18" upper is getting it's barrel pulled and the rest of the parts cannibalized for a 10.5" 300blk pistol build. My experiences hunting with and shooting these 3 resulted in my choosing a 20" barrel when I built my Aero M5 308.

[fledge]

The 20” is the original AR design and all the parts were designed for it. That probably is partly why he said that.

Also barrel whip can’t be underestimated when intimidating the enemy. :)

[Stickman]

@Stickman just out of curiosity are you joking or serious and if serious why do you think that?



I've got a 16" Govt profile, an 18" bull barrel and a 20" Hbar profile 5.56. Of the 3 my 20" is my favorite and has become a dedicated hunting rig for short range deer, hogs and predators. The 16" Govt profile is typically what I carry when hiking or stalk hunting and the 18" upper is getting it's barrel pulled and the rest of the parts cannibalized for a 10.5" 300blk pistol build. My experiences hunting with and shooting these 3 resulted in my choosing a 20" barrel when I built my Aero M5 308.

I think I have 4 20" uppers. I enjoy shooting them as they are very soft shooters, and as mentioned, original to the design. It was more tongue in cheek. I prefer 16" carbines.

[JMJ]

I think I have 4 20" uppers. I enjoy shooting them as they are very soft shooters, and as mentioned, original to the design. It was more tongue in cheek. I prefer 16" carbines.

Thanks!

[n4p226r]

I go 14.5” pinned myself!!!

[SINNER]

I’ve stamped all my 14.5’s. Never saw the logic in ruining a $400+ barrel and muzzle device to avoid a $200 stamp.

[Belanc]

I regularly run into guys who think the 16 inch barrel compromises the 556 in ballistics, others say the 20's are too long and heavy. To these guys maybe the 18 inch barrels seem like a good compromise.

I own one 18 inch/rifle length gas system rifle I bought to see how the rifle length system works on such a barrel. Unfortunately I have not been able to get to the range with it but I have high hopes for it. With the government profile barrel it doesn't feel any heavier than my 16 inch HB rifles so maybe it will offer a slight ballistic advantage without much penalty.

My current project about Tactics https://tacticsfaq.com/

[Former11B]

I regularly run into guys who think the 16 inch barrel compromises the 556 in ballistics, others say the 20's are too long and heavy. To these guys maybe the 18 inch barrels seem like a good compromise.

I own one 18 inch/rifle length gas system rifle I bought to see how the rifle length system works on such a barrel. Unfortunately I have not been able to get to the range with it but I have high hopes for it. With the government profile barrel it doesn't feel any heavier than my 16 inch HB rifles so maybe it will offer a slight ballistic advantage without much penalty.

I was using 18” barrels for my “distance” rigs but got some high quality 16’s and never looked back.

At 400 yards with a 3.5x ACOG, I was making 100% hits on an F-Type silhouette (head and shoulders profile) using 55gr FMJ, 69gr SMK through a 16” Rainier Ultramatch. Prone UNSUPPORTED. A quality barrel + quality ammo will get you the same results

[alamo5000]

I regularly run into guys who think the 16 inch barrel compromises the 556 in ballistics, others say the 20's are too long and heavy. To these guys maybe the 18 inch barrels seem like a good compromise.

I own one 18 inch/rifle length gas system rifle I bought to see how the rifle length system works on such a barrel. Unfortunately I have not been able to get to the range with it but I have high hopes for it. With the government profile barrel it doesn't feel any heavier than my 16 inch HB rifles so maybe it will offer a slight ballistic advantage without much penalty.


I was using 18” barrels for my “distance” rigs but got some high quality 16’s and never looked back.

At 400 yards with a 3.5x ACOG, I was making 100% hits on an F-Type silhouette (head and shoulders profile) using 55gr FMJ, 69gr SMK through a 16” Rainier Ultramatch. Prone UNSUPPORTED. A quality barrel + quality ammo will get you the same results

I wouldn't say 16" compromises anything. It all depends on what you are trying to do and in what conditions. If you shoot the same gun across all seasons the temperature variations alone will show a drastic difference at long ranges. The ability to engage a target within 500 yards or so in my opinion isn't compromised at all and you can shoot pretty much any factory ammo and still get hits on target.

My experience is much like Former11B. Good barrel. Good ammo. Good bullet. Good to go. I can routinely take my 16" gun out to 800 yards with my home rolled ammo. I haven't tried to go beyond that, but I think the possibility to hit 1000 yards is there with a 223/5.56 round out of the right gun with the right ammo on the right day. A longer barrel might help in that area, but not much else.

I am of the opinion that ammo compromises ballistics more than sheer barrel length. It just depends on the job at hand. Getting a 20+ inch barrel might allow me to hit a 1000 yards, but that is not really an effective range for that round for much of anything except saying you can do it. Engaging larger game/targets for any realistic distance isn't compromised in any appreciable way by a shorter barrel.

To me the longer barrel and slight velocity gain doesn't bring enough to the table to warrant me wanting to carry around a telephone pole. Even with a longer barrel, without highly tuned or selected ammo- at distance it just means you will miss your target at a meagerly higher velocity.

[Joelski]

Didn't Haley say that 300 BLK carries more energy at 500 than 5.56? Although it's just an effect of a heavier bullet, I shot a steel dumpster lid at about 330 yds the other day, and the audible feedback was impressive. The sheet metal was probably .015" or thereabouts, both rounds penetrated, but the 5.56 62 gr. bullet made a "tink", while the blackout made a hellofa racket. Not volunteering to be shot by either, but surgical findings continue to observe that non-instantly fatal shots result in remarkably less damage than ballistic gel would have us believe, especially in the category of tissue cavitation. This is true of all caliber projectiles short of the larger ones, at point blank range.

[Jerry R]

Just for point of reference ... our chrono findings in 2011

http://www.weaponevolution.com/forum/attachment.php?attachmentid=5456&d=1528910215

[HWS]

I read somewhere 16 inches is a sweet spot. The barrel is long enough to impart to the bullet most of the energy of a 20 inch, yet is is shorter and more easily swung around.

[voodoo_man]

We should all go back to 20" AR's

blasphemy, repent heathen and carry 10" guns!

[JGifford]

Anybody have an idea how 16 inches became the most common length for AR weapons? Why not 18 inches?



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*Serious Sounding White Guy Speaking Spanish Voice*


Es La Ley!

[JGifford]

Didn't Haley say that 300 BLK carries more energy at 500 than 5.56? Although it's just an effect of a heavier bullet, I shot a steel dumpster lid at about 330 yds the other day, and the audible feedback was impressive. The sheet metal was probably .015" or thereabouts, both rounds penetrated, but the 5.56 62 gr. bullet made a "tink", while the blackout made a hellofa racket. Not volunteering to be shot by either, but surgical findings continue to observe that non-instantly fatal shots result in remarkably less damage than ballistic gel would have us believe, especially in the category of tissue cavitation. This is true of all caliber projectiles short of the larger ones, at point blank range.

Depends on the bullets. A lot of what people THINK is based on data that is incorrect. I've been sending off various rounds to be doped by people with the time and money to do it, and it's shocking what their actual BC's are vs. advertised BC's. I do not double-check my contact's work, but the data he is getting me is within 1% of Bryan Litz data on the projectiles they have both doped, when I compare them.