BRT OPTIMUM Barrels

[Biggy]

Will we still be seeing BRT 11.5" OPTIMUM CQB-S, tapered shoulder barrels at some point in the near future ?

[Clint]

Will we still be seeing BRT 11.5" OPTIMUM CQB-S, tapered shoulder barrels at some point in the near future ?

Working on some final details and counts now.



It would be possible to do these in an EXC (Extended CAR) gas system that would be better for dedicated suppressed use.

Who's looking to use these as dedicated suppressed vs more general purpose?

[opngrnd]

I went out and shot 10 5-shot groups today after throwing a cheap Burris 3x9 on my Optimum LW build. My takeaways are to invest in a decent set of squeeze bags, or at least a good rear bag. I can always throw a bipod on the front. The bags I have are too hard and I find my natural POA shifting during strings of fire, leading to flyers.
Attachment 57795
Attachment 57796

Flyer-free groups brought the average back down.
Attachment 57797

Ammo was a mix of handloads and reman ammo. With flyers, average is 1.76". Without obvious flyers, average is 1.34". I'm actually surprised how well the barrel shoots, it has the toughest service life of any of my rifles, has about 3500 rounds through it, and is what I use for drills, 3 Gun, etc. I'll probably throw the RDS and LMT BUIS on and drive forward at this point.

[MQ105]

It would be possible to do these in a CAR+1" gas system that would be better for dedicated suppressed use.

Who's looking to use these as dedicated suppressed vs more general purpose?

I intend to run one with a direct-thread can. Is "CAR+1" shorter than mid?

[Clint]

Yes, EXC length is halfway between CAR and MID.

An 11.5" EXC has similar Power Time (dwell time) to a 10.5" CAR or 12.5" MID.

Also, a Q Cherry Bomb or similar taper mount brake adds ~ 0.5" effective barrel length when the QD suppressor is removed.

I intend to run one with a direct-thread can. Is "CAR+1" shorter than mid?

[Clint]

A little more on the EXC gas system...


The effects of using a suppressor can be thought of as similar to adding barrel length, say 3", making a suppressed 11.5 setup act more like a 14.5" CAR.

Running a dedicated small port in the Carbine gas system effectively compensates for the increase in available gas drive caused by the suppressor.

A 14.5" CAR with a proper port can run, but is not ideal.



The longer EXC gas system directly offsets the increase in available gas drive caused by the suppressor, but more importantly, it helps restore proper timing to the cycle, which a CAR length gas system can never do.

[Clint]

For those interested.

Free gas tube with every barrel
and
Free shipping on orders over $100

https://mailchi.mp/be8ed2982705/inde...-free-shipping

[1168]

Clint, I’ve been thinking about how a suppressor adds effective barrel length, as far as the gas system sees it. If you were “building” a 10.3” with a YHM Turbo K 100% suppressed (total length ~14.5”), and could set the gas port at whatever you want, would you spend the extra money on a LMT E-BCG over a regular one? I’m considering it since that carrier was designed for a 14.5” carbine gas barrel. What about a 75% suppressed 11.5” with a Griffin M4SDk? Thats around 16.5”, and nearly all available barrels have carbine gas.

[1168]

An update to my precision (accuracy) results posted earlier: Yesterday morning, I cleaned the bore of my Optimum Light 16”, mounted a Leupy 14x scope and headed to the range. It was testicle-drenching hot. No wind. All the humidity. I shot from the prone using a Bog Pod with a woobie over concrete at 100yds. I fired 5 shot groups instead of 10, because I was pouring sweat. I rough zero’d with singles, then fired 1 group of American Eagle M193 clone(edit: this was actually Aguila 62gr 5.56), 4 groups of Hornady 75gr Superformance 556 BTHP Match, and 2 groups of PMC .223 77 SMK.

Aguila: 1.6”
Best Hornady: 0.9”
Best PMC: 1.5”

The other PMC group looked exactly like the best Hornady group until I chucked a flyer high and right. I feel like it could shoot MOA, with more patience. The other 3 Hornady groups were 1.5”-2”. Looking at the results, it would appear that the shooter is the limiting factor here.

I have a little more “match” ammo, and I’ll update as I shoot more of it, either today or Thursday, depending on if I can get to the range later.

[Clint]

Yes, suppressors add some equivalent barrel length due to the extra pressure, which may or may not be related to their physical length.


For a 10.3-11.5" barrel, the new equivalent length might be 14.5, but could also be 13"-16" depending on the suppressor or ammo.

So the question can be re-framed as, making a new 14.5" barrel would you rather give it a CAR gas system and use the E-BCG or a give it MID gas system and use a standard BCG?

If the E-BCG was designed to compensate for a non ideal gas configuration, a better and more direct approach when starting from scratch is to use the ideal gas configuration instead.

The E-BCG can have some benefits, but they don't seem to be there in properly configured and ported gas systems.

For overall performance and value, a 14.5" MID with a standard BCG beats a 14.5 CAR with a special BCG.


That's really the logic behind the EXC gas system for a dedicated suppressed barrel; to get the gas system in a more ideal place for how it will actually operate.

Clint, I’ve been thinking about how a suppressor adds effective barrel length, as far as the gas system sees it. If you were “building” a 10.3” with a YHM Turbo K 100% suppressed (total length ~14.5”), and could set the gas port at whatever you want, would you spend the extra money on a LMT E-BCG over a regular one? I’m considering it since that carrier was designed for a 14.5” carbine gas barrel. What about a 75% suppressed 11.5” with a Griffin M4SDk? Thats around 16.5”, and nearly all available barrels have carbine gas.

A little more on the EXC gas system...

The effects of using a suppressor can be thought of as similar to adding barrel length, say 3", making a suppressed 11.5 setup act more like a 14.5" CAR.

Running a dedicated small port in the Carbine gas system effectively compensates for the increase in available gas drive caused by the suppressor.

A 14.5" CAR with a proper port can run, but is not ideal.

The longer EXC gas system directly offsets the increase in available gas drive caused by the suppressor, but more importantly, it helps restore proper timing to the cycle, which a CAR length gas system can never do.