BRT OPTIMUM Barrels

[Clint]

Thanks for the range report.

The consistency and smoothness is really remarkable.

The Perma-Grin a pretty normal result after shooting an OPTIMUM barrel

My buddy, for whom I built a BRT Optimum 16" gen-1 centered gun, loved it!

Forged upper and lower, BRT EXT Optimum barrel and MicroPin BRT gas block, ALG rounded top handguard (the exact model escapes me; it was mlok, lol), PWS H2 Buffer, Sprinco Blue action spring, std nitride carrier with Sprinco 5-coil extractor spring, and Precision Armament AFAB 556 (current generation). PA ACSS 3x prism fakeCog on top.

With full power federal Brown box M193, the first thing my buddy blurted out (in that barely controlled, childlike fashion) was "this damn thing kicks less than my 10/22!!!!" with a fairly dumb grin on his face. Things devolved from there.... including grown men giggling.

It basically just vibrates in your hand. With .223 pressure AE Ammo it feels like it's short stroking, but ejection is strong @ 3:30-4:00 and it locks back on empty even with no shoulder purchase. Brass collects in a bucket if you don't move.

[BufordTJustice]

Thanks for the range report.

The consistency and smoothness is really remarkable.

The Perma-Grin a pretty normal result after shooting an OPTIMUM barrel

It's KAC small-port levels of smoothness.

My buddy actually shot his 10/22 back to back against his BRT rig. Even with full house Nato pressure federal xm193, he swears his BRT rig both: 1) shoots softer in terms of rearward recoil and 2) has less axial movement of the reticle.

He described the reticle of the 3x PA FakeCOG ACSS as just "vibrating on target" on his BRT 16" rig.

He said he's watching bullet impacts from offhand shots at 150 yards even with a relaxed stance and cannot wait to take a deer with it this season. He'll be using 75gr Gold Dots.


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[opngrnd]

It's KAC small-port levels of smoothness.

My buddy actually shot his 10/22 back to back against his BRT rig. Even with full house Nato pressure federal xm193, he swears his BRT rig both: 1) shoots softer in terms of rearward recoil and 2) has less axial movement of the reticle.

He described the reticle of the 3x PA FakeCOG ACSS as just "vibrating on target" on his BRT 16" rig.

He said he's watching bullet impacts from offhand shots at 150 yards even with a relaxed stance and cannot wait to take a deer with it this season. He'll be using 75gr Gold Dots.


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I've only shot one rifle like that. It was a 3gunner's rifle set up around a specific load on the ragged edge of function. And in accordance with Murphy, it malfunctioned during a big match he was doing well in. I'm actually about to throw a SF muzzle brake on my BRT Optimum build for the incoming SOCOM suppressor, looking forward to it.

[AKDoug]

Clint- Is there any performance loss running the 7.62 covert comp on the 5.56 16" SPR barrel (I already ordered) since the new barrels come with the larger 5/8 threads?

[Clint]

The 7.62 works fine, but the Covert Comp 6X is the best choice for all barrels with 5/8-24 threads.

We put the 6X on pre-order with free shipping, so you can grab one on a separate order.

Clint- Is there any performance loss running the 7.62 covert comp on the 5.56 16" SPR barrel (I already ordered) since the new barrels come with the larger 5/8 threads?

[Clint]

This is a good example of the synergy between a very effective brake and the OPTIMUM gas system.

Unlike many over tuned 3 gun setups, OPTIMUM barrels maintain full reliability margin, while being extremely smooth.

Good things happen when the AR system operates at optimal timing, rather than fighting itself.

My buddy actually shot his 10/22 back to back against his BRT rig. Even with full house Nato pressure federal xm193, he swears his BRT rig both: 1) shoots softer in terms of rearward recoil and 2) has less axial movement of the reticle.

He described the reticle of the 3x PA FakeCOG ACSS as just "vibrating on target" on his BRT 16" rig.

I've only shot one rifle like that. It was a 3gunner's rifle set up around a specific load on the ragged edge of function. And in accordance with Murphy, it malfunctioned during a big match he was doing well in. I'm actually about to throw a SF muzzle brake on my BRT Optimum build for the incoming SOCOM suppressor, looking forward to it.

[AndyLate]

You guys are pushing me to complete my stalled upper build.

The parts I have on hand are:

BRT 16" Light Optimum barrel/gas block/ gas tube
BCM M4 upper receiver
ALG 12" V2 M-LOK Handguard
Sionics phosphate BCG
Trijicon 1-4 Accupower in a Warne X-SKEL fixed mount

The parts I still need are:

Charging handle
Muzzle device

I plan on a simple forged charging handle and an A2 flash hider.

I want to take the barrel/gas block in to my friendly neighborhood machinist and get them drilled for a pin (I have BRT pins on hand as well), and to pick up a reaction rod. I put my last upper together with a "clamshell" and was underwhelmed.

The lower I will pair it with is currently an A5 H2 setup with a Larue MBT two-stage trigger.

It should be a nice set up when I finish it.

Andy

P.S. I should be able to make some valid comparisons - I also have a 16" BCM mid length and a 16" FN/PSA barreled carbine with the gas drive "corrected" via BRT port.

[Clint]

OPTIMUM Profile Explained

Efficiency is a hot topic these days, whether it be "efficiency of motion" when practicing tactical skills or the fuel efficiency and range of your favorite SHTF vehicle.

The OPTIMUM profile could be described as "efficiency of design", producing maximum stiffness for any given weight.
It's easy to make a very stiff barrel by just piling on the material to make a very thick profile that weighs too much.

It is often said the .GOV profile is backwards, being thinner near the chamber and thicker towards the muzzle.
This is true, but mostly in the case of simple bending of the muzzle while holding the chamber.
The good real world performance can be partially explained its good performance in other types of bending.

We developed a few standard tests to compare the performance of various profiles under simulated loading.
Both deflection and stress levels are evaluated.
A balanced barrel will perform well across all three tests.
We used the 16" MID GOV profile as a baseline of performance for comparing the OPTIMUM profiles.
The 16" mid length and 16" M4 versions perform nearly identically.


Test one holds the barrel extension fixed while loading the muzzle downward with 10 pounds of force.
This represents simple bending. Stress intensity is shown. (Green arrows are fixtures. Purple arrows are forces)

As expected, the GOV profile performs relatively poorly in test one.
The thin area between the chamber and gas block is highly stressed (shown in green, yellow and red) compared to the rest of the barrel (shown in blue).

An OPTIMUM profile of the same weight would be 20% stiffer.
Our MPR profile adds 2 ounces and is 55% stiffer in this test with a much less intense and more evenly distributed stress area.


Test two holds the barrel extension fixed (like in test one) while loading the muzzle with a bending torque that attempts to force the barrel into an "S" or question mark like shape.
This torque is produced from a combination of a downward force of 140 pounds at the muzzle and an upward force of 140 pounds at the thread shoulder.
This represents a more complex bending that may be similar to barrel whip with a suppressor attached.

The GOV profile does better in test two, thanks to the relatively large diameter towards the muzzle.
The thinner chamber area and the muzzle threads show the areas of most stress.

Our MPR profile improves on this already good performance by measuring 43% stiffer in this test and showing much more even stress distribution along the full length.



Test three holds the muzzle threads fixed while loading the breech downward with 5 pounds of force, basically the opposite of test 1.
This is again simple bending, but really stresses critical muzzle area.

The GOV profile also does pretty will in test three, but shows very high stresses directly under the muzzle thread shoulder.
This is largely the result of the mismatch between the small 1/2-28 threads and the much thicker portion of the barrel directly behind the thread shoulder.

Our MPR profile bests this with a 21% improvement is stiffness in this test and nearly 50% lower stress at the muzzle thread shoulder, thanks to the sturdy 5/8-24 threads and careful contouring behind the shoulder.

[Clint]

Suppressor Ready Threads

There are several features required to properly support suppressor attachment.

Obviously the threads and shoulder need to be concentric and square to the bore.

Tighter clearance thread pitch assures good alignment of the muzzle device and the bore.


Most suppressor mount muzzle devices require indexing.

This is almost always accomplished via shims.

The Precision Armament shims are among the best, using a single thick shim, rather than a stack of paper thin shims.

The junction of the threads and thread shoulder must allow the shim to sit flat against the shoulder, while also supporting the shim's inner diameter to keep it concentric.


OPTIMUM barrels have all these features and more.


In addition, most OPTIMUM barrels utilize larger 5/8-24 threads, which create a much stronger connection and affect the bore much less than common 1/2-28 threads.

[scooter22]

Clint, can you comment on the ballistics and reliability of the 9” and 6.75” offerings?


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