14.5” AR-15 Barrels With Permanently Attached Muzzle Devices

AR/M4 AR General Discussion
1

Accuracy Evaluations of 14.5” AR-15 Barrels With Permanently Attached Muzzle Devices

The unwashed masses in my state are not allowed to own SBRs, therefore the shortest commonly available AR-15 barrels that I can legally posses are 14.5” barrels; with permanently attached muzzle devices that bring the overall length up to the legal length. For this article, we’ll be looking at four different chrome-lined, NATO chambered, 14.5” AR-15 barrels with permanently attached muzzle devices:

> Noveske 14.5” “Skinny” barrel

> Noveske 14.5” N4 “Light” barrel

> Bravo Company 14.5” “government profile” barrel

> Colt 14.5” M4A1 SOCOM barrel

The Noveske barrels evaluated have permanently attached Smith Enterprise Vortex flash-hiders. The Bravo Company barrel evaluated has a permanently attached BCM A2X flash-hider and the Colt M4A1 SOCOM barrel evaluated has a permanently attached Young Manufacturing flash-hider.

All of the barrels were evaluated utilizing free-float hand-guards and match-grade hand-loaded ammunition. All testing was conducted from the bench at a distance of 100 yards.

I conducted the accuracy (technically, precision) evaluations of the four different barrels listed above following my usual protocol. These accuracy evaluations used statistically significant shot-group sizes and every single shot in a fired group was included in the measurements. There was absolutely no use of any group reduction techniques (e.g. fliers, target movement, Butterfly Shots).

The shooting set-up will be described in detail below. As many of the significant variables as was practicable were controlled for. For these accuracy evaluations, I used one of my standard match-grade hand-loads topped with Sierra 55 grain BlitzKings. When fired from my Krieger barreled AR-15s, this load has produced ½ MOA 10-shot groups at 100 yards.

All shooting was conducted from a concrete bench-rest from a distance of 100 yards (confirmed with a laser rangefinder.) The barrels used in the evaluations were free-floated. The free-float hand-guards of the rifles rested in a Sinclair Windage Benchrest, while the stock of the rifle rested in a Protektor bunny-ear rear bag. Sighting was accomplished via a Leupold VARI-X III set at 25X magnification and adjusted to be parallax-free at 100 yards. A mirage shade was attached to the objective-bell of the scope. Wind conditions on the shooting range were continuously monitored using a Wind Probe. The set-up was very similar to that pictured below.

The Wind Probe.

The Colt M4A1 SOCOM barrel

A genuine Colt M4 SOCOM barrel is 14.5” long and has a medium contour underneath the handguards (not a heavy barrel profile). The barrel has a NATO chamber and a 1:7” twist. The SOCOM barrel has the typical M4 circumferential cut-out located approximately 1.4” forward of the gas block for the attachment of an M203, as well as rectangular shaped cut-outs underneath the handguards on the port and starboard sides of the barrel, located approximately 1.4” aft of the gas block, for the same reason. The SOCOM barrel employs the carbine length gas system.

The barrel stamp located just aft of the flash suppressor reads:

         C   MP

5.56 NATO 1/7

The barrel has an “F” marked front sight base and a side sling swivel. The “F” mark is located on the port side of the front sight base.

The SOCOM barrel will have a “date code” located immediately aft of the handguard retaining ring. The handguard retaining ring itself will also have cut-outs located at 4:30 and 8:30; again for the attachment of an M203.

The barrel will also have a small “O” stamp, that is located at the chamber section of the barrel, indicating a chrome-lined chamber and bore.

Naturally, the SOCOM barrel will have M4 feedramps and there will be a numeral “4” stamped at the 3 o’clock position on the barrel extension.

Here are a couple pics comparing the SOCOM barrel to the standard M4 barrel.

The Colt 14.5" M4A1 SOCOM barrel used in this evaluation was free-floated during testing using a Daniel Defense Omega free-float railed handguard. Using the match-grade hand-loads, I fired three 10-shot groups from the Colt SOCOM barrel at a distance of 100 yards. Those groups had extreme spreads of:

0.90”
1.02”
0.93”

for a 10-shot group average extreme spread of 0.95”. All three of the 10-shot groups were over-layed on each other using RSI Shooting Lab to form a 30-shot composite group. The mean radius for the composite group was 0.35”.

The smallest 10-shot group.

The 30-shot composite group.

continued . . .

2

Noveske 14.5” N4 Light Barrel

For starters, Noveske’s nomenclature of “Light” for this barrel is somewhat misleading/confusing. When most shooters hear the term “light- weight” in regard to AR-15 barrels, they think of the “pencil” barrel profile of the original Colt M16/M16A1 and also the same light-weight profile of the Colt 16” carbine barrel found on the Colt 6520 and 6720. However, this is not the profile of the Noveske N4 Light barrel.

Colt M16/M16A1 barrel . . .

Colt 6520 16” light-weight barrel . . .

Noveske’s N4 Light profile was designed to produce better accuracy than a government profile barrel without adding any weight. The 14.5” and 16” N4 Light barrels have the same weight as Colt 14.5” and 16” government profile barrels.

As you can see in the pics below (16” version pictured), for the N4 Light barrel, Noveske has done away with the next-to-useless M203 (grenade launcher) cut-out found on the Colt government profile barrel. The N4 profile also has a more evenly distributed barrel diameter (and thus weight) fore and aft of the gas block journal, which moves the center of gravity of the barrel farther aft compared to a government profile barrel. This all makes for a superbly handling barrel.

Colt 6920 government profile barrel . . .

Noveske 16” N4 Light barrel . . .

The reason that Noveske uses the “Light” nomenclature for their N4 barrels is simply because the N4 barrels are lighter than Noveske’s original medium contour stainless steel barrels.

The Noveske 14.5” N4 Light barrel is a cold hammer forged barrel. It has “M4” feed-ramps and a chrome-lined chamber and bore. The barrel has a 5.56mm NATO chamber and a 1:7” twist and has been high-pressure/magnetic particle tested; as the barrel stamp indicates. Contrary to erroneous Internet reports, the N4 barrel does not have polygonal rifling.

The barrel stamp . . .

The Noveske 14.5” N4 Light barrel used in this evaluation was free-floated during testing using a Larue Tactical free-float railed handguard. Three 10-shot groups fired from 100 yards using match grade hand-loads had extreme spreads of:

1.029”
1.360”
1.275”

for a 10-shot group average of 1.22”. As above, I over-layed the three 10-shot groups on each other using RSI Shooting lab to form a 30-shot composite group. The mean radius for that composite group was 0.37”.

……

Bravo Company 14.5” Barrel

This is the cold hammer forged (BFH) version of Bravo Company’s 14.5” barrel with a mid-length gas system. As can be seen in the pic above, this barrel has a government profile. This is a chrome-lined, NATO chambered barrel with a 1:7” twist. Bravo Company states that these barrels have been high-pressure/magnetic particle tested according to the current mil-spec.

The Bravo Company 14.5” barrel used in this evaluation was free-floated during testing using a Daniel Defense Omega free-float railed handguard.

Three, 10-shot groups of the match-grade hand-loads were fired in a row from the Bravo Company 14.5” barrel from a distance of 100 yards with the resulting extreme spreads:

1.58”
1.96”
1.50”

for an average 10-shot group extreme spread of 1.68”. The three, 10-shot groups were over-layed on each other using RSI Shooting Lab to form a 30-shot composite group. The mean radius of the 30-shot composite group was 0.49”

The smallest 10-shot group . . .

The 30-shot composite group . . .

….

Noveske 14.5” “Skinny” Barrel

Noveske’s “Skinny” barrel is their version of the light-weight “pencil” profile barrel. This barrel is a cold hammer forged barrel. It has “M4” feed-ramps and a chrome-lined chamber and bore. The barrel has a 5.56mm NATO chamber and a 1:7” twist and has been high-pressure/magnetic particle tested. The barrel has traditional rifling.

The Novekse 14.5” “Skinny” barrel was tested while wearing a Centurion free-float rail. For this barrel, I fired eight 10-shot groups in a row from the bench at a distance of 100 yards using the match-grade hand-loads. The extreme spreads for those eight groups were as follows:

1.78”
1.89”
1.68”
1.71”
1.81”
2.12”
1.60”
1.84”

for an average extreme spread of 1.8” and a composite mean radius of 0.55”.

……

Some additional data for comparison. (All barrels were free-floated during testing.)

…

3

Thank you once again for sharing your information with everyone.

4

Da nada.

…

5

As usual…great thread:cool:

Cheers
Shannon

6

Excellent. Thanks for taking the time to share this.

7

Interesting results. It seems that all the CHF barrels are not nearly as accurate as standard button cut barrels. Or maybe just colt barrels are just really that good.

8

I’ve heard good things about those SOCOM barrels. That is surpassing accuracy.

9

I chalked that up to the heavier profile.

10

Here are some additional data points on the accuracy of various barrel profiles of chrome-lined, NATO chambered barrels for comparison; this time from 16” barrels. (All barrels were free-floated during testing.)

Colt 16" light-weight barrel (6520)

Colt 16" government profile barrel (6920)

Colt 16" HBAR (6721)

…

11

Always love your reports…useful facts every time.

12

Thanks Molon. The accuracy of the Socom barrel is impressive for a chrome lined 5.56 barrel.

13

The SOCOM barrel I used in 2011-12 was super accurate too.

I like that report. Kinda disproves most of the general wisdom in the ‘which barrel should I get’ threads.

14

Good job as usual Molon. Let me pick your brain. I understand how barrel harmonics can affect accuracy and a heavier profile has better dampening properties than a skinny one but for practical purposes is the difference worth talking about? If you took that Krieger barrel you have and spun it down to a pencil profile without touching the existing crown or chamber how much do you think it would fall off?

15

I second GH41’s questions, I am very curious as to what the answer may be.

Great info as always Molon!

16

That’s for you to decide for your particular application. Keep in mind that my groups were fired in a slow, steady manner. Once you start heating up your barrel with more rapid firing, the different barrel profiles are going to handle the increased heat differently.

Also, all the barrels were free-floated during my testing. Again, the different barrel profiles are going to respond differently, this time to external forces, when not free-floated

Probably a significant amount, but I’m not going to ruin one of my Kreiger barrels to find out.

…

17

As usual a very interesting and informative post. Thank you for sharing your data with us.

18

Does a heavier barrel have better damping properties than a light barrel? Obviously it’s more rigid, but spring rate and damping are significantly different.

19

So, you mean to tell me that the NON FREE FLOATED barrel was the most precise?

Heresy!

As always, thanks Molon. Excellent post!

20

No, he doesn’t mean to tell you that…

…because it was free floated. They all were.