So I have my .308 12.5" SBR torn apart to change handguard and muzzle brake and had a question about the barrel.  The current barrel is a 12.5" 416SS mid-length gas CMMG barrel.  I see Ballistic Advantage sells a 4150 12.5" with a carbine gas length.  Would the BA barrel with carbine gas be better all around?  I do have an SLR adjustable gas block on there if makes a difference and the rifle will be primarily shot suppressed.  Before the adjustable gas block the rifle did cycle too fast and caused malfunctions when suppressed.  Another issue I have and hoping the adjustable gas block will help is it was constantly breaking the bolt catch.  I'm asking because if the BA barrel would be better now is my time to swap since it's torn down.

If anything the carbine-gas barrel will cause even more rapid cycling, depending on its port size of course. If you already have your system pretty dialed-in, there's no reason to buy a new barrel just for a shorter gas system.

I have the CMMG 12.5" .308 barrel and SLR Sentry 7 gas block as well. I switched my standard length buffer tube, .308 spring, and .308 shorty buffer with a VLTOR tube, Sprinco Orange spring, and a PWS H4 standard length buffer. It has slowed the speed of the bolt for sure. I need to do some additional testing but the current setup is much more reliable than the previous setup. The Sentry 7 is still dialed down as it was before.

I ordered the BA 12.5" barrel with carbine length gas and I also ordered the Lantac Enhanced BCG.  We'll see how that combo works.

I also have a12.5” 308 and besides all the mods you did another one that helped mine the most was an expanded gas tube from I bought from Midway.  That slowed my system down tremendously.

Your bolt catch is breaking because the bolt is traveling too far rearward thus giving it a longer run into the bolt catch when the rifle runs empty. Superior Shooting Systems 308 spring cut to just allow the catch to clear the bolt will fix this..

May have to try one.  I did order a bolt catch made from S7 tool steel from V Seven.

308 SBR's are fun, but they are loud . Suppressors will be your friend.

I have a 12.5" with Rainier barrel. Prior to the adjustable gas block i broke a bolt catch and also somehow broke a piece of the locking lug off the bolt so it wouldn't feed a round. The bolt was traveling sooo fast I dont even think it was ejecting the case (if i remember correctly) the recoil was also hell.  I decided to go with SLR adjustable and the JP silent capture spring with the additional spring pack. I think im running the middle stiffness spring and the rifle runs like a sewing machine!

I just ordered the JP silent capture spring H2.