What Barrel Length for Next SBR?

[squid8286]

I like the 11.5. It shoots flatter and hits harder at 300 yards than the 10.5. With an adjustable gas block and an A5 RE, it's surprisingly soft and smooth, even with a suppressor.

The 6933 upper works well with an H buffer and even better with a H2, but it's over gassed with a suppressor.

In your experience with a 6933 upper, do you see a need to ever use a buffer as heavy as an H3 when using it non-suppressed? Would this help with the over-gassing situation you mentioned WITH suppressor use?

[officerX]

Looking at 12.5" barrels - I can get a BA for $135 shipped or a BCM for $252 shipped. I've used the BA barrels before and have no issues with them or with buying another. My SBR lower is a BCM and I love BCM products. I'll probably buy a blem BCM upper and build with it (if/when in stock), and will probably get a KMR. Should I pay almost double and get the BCM barrel?

What do you guys think about this? Almost everything else on the gun will be BCM. Should I get a BCM barrel too or a cheaper Ballistic Advantage barrel?

[308sako]

What do you guys think about this? Almost everything else on the gun will be BCM. Should I get a BCM barrel too or a cheaper Ballistic Advantage barrel?

I have had excellent results with a half dozen BCM barrels and one that wasn't so hot. As to the Ballistic Advantage, I really want to try one, but have not as yet. I would say it depends upon what level of performance you are looking for, and to me it is all about the weight and balance of the finished rifle.

[MistWolf]

In your experience with a 6933 upper, do you see a need to ever use a buffer as heavy as an H3 when using it non-suppressed? Would this help with the over-gassing situation you mentioned WITH suppressor use?

A heavier buffer will help an overgassed AR, but won't fix the problem.

I did not test the 6933 unsuppressed with anything but the H buffer. It worked, but I think it would have been better with a Sprinco blue spring and/or an H2.

An H3 buffer is about the same weight as a rifle buffer and an A5H2. I did not test anything with an H3 buffer. If the weight of an H3 is wanted or needed, I think it's better to go with an A5H2 or rifle buffer.

The 6933 upper was tested with the A5H2 buffer and Sprinco green, but carrier speeds were too high. The buffer was banging far too hard against the RE and recoil was sharp. Even with the A5H2, it was overgassed. I used a .063" micro port from BRT and it helped tremendously, but I'm thinking I want to go smaller. So, the answer is, a buffer in the same weight class as an H3 should be fine with the 6933 upper unsuppressed. However, it isn't enough when a suppressor is used.

[drtywk]

What do you guys think about this? Almost everything else on the gun will be BCM. Should I get a BCM barrel too or a cheaper Ballistic Advantage barrel?

If you can find one, I have had great luck with the Centurion Arms 12.5” barrels. CA doesn’t offer them anymore though. FN does, as does Daniel Defense. In saying that, I wouldn’t hesitate to use the BCM or Ballistic Advantage barrels either. The BA barrel is $150 and can be had for less during their sales.

[squid8286]

A heavier buffer will help an overgassed AR, but won't fix the problem.

I did not test the 6933 unsuppressed with anything but the H buffer. It worked, but I think it would have been better with a Sprinco blue spring and/or an H2.

An H3 buffer is about the same weight as a rifle buffer and an A5H2. I did not test anything with an H3 buffer. If the weight of an H3 is wanted or needed, I think it's better to go with an A5H2 or rifle buffer.

The 6933 upper was tested with the A5H2 buffer and Sprinco green, but carrier speeds were too high. The buffer was banging far too hard against the RE and recoil was sharp. Even with the A5H2, it was overgassed. I used a .063" micro port from BRT and it helped tremendously, but I'm thinking I want to go smaller. So, the answer is, a buffer in the same weight class as an H3 should be fine with the 6933 upper unsuppressed. However, it isn't enough when a suppressor is used.

Thank you.

[Pappabear]

I've run 10.3 and every possible configuration. Don't really notice much difference. Like Clint said, it's about proper gas port with barrel length. That's where it's important. BCM doesn't make anything shorter than 11.5, because the idea it gets more finicky.

PB

[officerX]

OP what caliber?

In 5.56 a 11.5”
In 300 Blackout 8.5”
In 9mm a 4.5”



Do it! I have two in 9mm. Well the CZ is a pistol.




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Nice SLM1 you've got there in the bottom pic!

[usmcvet]

Nice SLM1 you've got there in the bottom pic!

Thanks. Did I buy it from you? It's really a cool option and keeps things streamlined.

[officerX]

Thanks. Did I buy it from you? It's really a cool option and keeps things streamlined.

Nope, I’ve been buying every one I can find. I got one from Rosch before they went out of business. I’ve gotten 2 more from EE threads here and TOS.