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BCM MCMR handguard and 6arc proof carbon barrel compatibility

Jnull

Gunny Sergeant
Full Member
Minuteman
Jul 22, 2020
683
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Thinking about putting together one of my ARs in 6 arc using an 18” proof carbon barrel. The rail I have is a BCM mcmr mlok which is pretty slim, I doubt theres any problem fitting the barrel in there but what about an adjustable gas block? I just got my flow 762 approved yesterday but usually run adjustables on all my rifles. I also have a JP SCS with standard weights for it.

I’ve been on beer city bullets wait list for their barrel for months so I’ve about given up on them, plus the proof is 6.5oz lighter but almost double the cost. This rifle will probably primarily get used for night hunting.
 
I'm running a KMR on a stainless Proof barrel no issues. I run superlative adjustable gas blocks under my KMRs no issue. I'm sure SLR would work the same and the MCMR handguards are pretty much the same
 
I'm running a KMR on a stainless Proof barrel no issues. I run superlative adjustable gas blocks under my KMRs no issue. I'm sure SLR would work the same and the MCMR handguards are pretty much the same

Are the stainless about the same profile as the carbons do you know?
 
I'm running a 20" Proof carbon under the 15" MCMR with an Aero adjustable block. You may need to take some material off the threads on MLOK attachments depending on where it is on the handguard/barrel.
 

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Are the stainless about the same profile as the carbons do you know?
Not sure, but I've run an RRA predator pursuit barrel under the KMR's with no issues. As long as the gas block journal is 0.750" you should be good
 
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I'm running a 20" Proof carbon under the 15" MCMR with an Aero adjustable block. You may need to take some material off the threads on MLOK attachments depending on where it is on the handguard/barrel.

That’s not a big deal I have to do the same on my Christensen with a carbon barrel and slim handguard. That’s been my coyote gun for a few years now.