AR-15 BS Thread

10.5 is fine with 300BLK, I’ve had no issues with mine. Now I’m building an 11.3” 5.56

 

Nice, that’s funny that was actually the other option I was looking at.

 

A 300 black in 10.5 would be sweet, for 5.56 I prefer 11.5 if suppressed or 12.5 if not.

 

My “long” gun is a 13.7” pinned to 16”. The 11.3 with have an ASR mussel brake installed.

 

In retrospect, I kind of wished that I went with an 11.5 on my 5.56 pistol build before transitioning it to SBR, only for the fact that that extra inch holds up the velocities better.

 

The barrel I wanted came in 11.3 and not 11.5.

With an 8” can, I didn’t want to go any longer.

 

Mines similar, 14.5 pinned running a suppressor and then 11.5 is the same thing

 

It seems to shoot about ~1MOA with 168gr Fed. Match.

 

From what I’m reading, 11.5 sounds to be the magic number when building a pistol if you plan on adding a suppressor...

10.5 may fall a little short in length and not provide the stability for distance shots while keeping it a smaller/lighter fire arm

 

if you're going to suppress a short barrel (either SBR or pistol) just make sure the suppressor is rated for at least the barrel length you are using. Most 5.56 cans (or at least most when I was reading up on barrel length a while back) are only rated to 11-12" or so. Even 30cal cans might have a minimum length requirement for 5.56 in addition to .308.

 

get some good ear protection.

 

Personally I’d go with 11.5” if you plan to run a suppressor and 12.5” for a naked gun.

 

It's only a barrel change away to get you to 11.5. My upper was originally a 10.5, but I change the barrel to an 11.5. slowly after that I changed out everything else over time to where the only original part of the factory 10.5 upper is the receiver now. But i'd be willing to bet you could find someone to trade you or sell your 10.5 and get an 11.5 barrel of the same quality without coming out of pocket.

 

The issue at this point is based on the fact that the Form 1 paperwork for an SBR specifically addresses barrel length, and unless I submit a change to the Form 1 and pay the additional money ($200), I can not legally change the barrel out for the 11.5.

 

I was not aware of that. That sucks. I guess you can build an 11.5 upper too as long as you keep the 10.5 upper right? Everyone needs more uppers right?

 

It is my understanding that you may change the configuration of your SBR.

My SBR is registered as a 7.5” barrel, however my 11.5” is on it fairly often as is my 12.5” 6.8 upper.

https://blog.princelaw.com/2012/12/...gth-of-an-short-barreled-rifleshotgun-sbrsbs/

 

you can change it but you have to be able to change it back. I have a 300sbr, but I also have a 5.56 Larue barreled upper for it.

 

^^^ this
Most .308 cans are only rated to 16 or 14”, there are a handful without barrel ratings but staying 14”-16” is best for performance anyway.

 

Oh no, my apologies for the confusion, I'm going with an 18" criterion barrel with a JP gas block for the AR-10 platform. I've already built the 300blk pistol, love that gun, just need to add an adjustable gas block later on.

 

Gotcha! If you're going to buy a suppressor, might as well make the 10 a host too! What caliber?