Running a BCM BFH 11.5 and only shoot it suppressed. Running an
H3 buffer… Was shooting Remington .223 UMC. No cycling / function issues but the groups were all over the place. (I know this isn’t a precision platform…)
Switched to Federal XM193… Has excellent repeatable groups… but the bolt will not lock back on empty magazines. Tried an H2… Then tried a standard (no marking) buffer… Locks back but not all the time.
I took the Magpul BAD lever off as I have had issues with that before but again, everything cycled great on the UMC!
I’m new at the SBR thing and know that there needs to be some troubleshooting done here… What am I missing?
Your group issue is due to the ammo or your shooting. My original 11.5" was the same configuration. I was using an AAC M4-2000 and an H3 buffer. I had 100% lockback and no issues at all. I was using a Springco blue spring.
As for accuracy my experience and that of others has shown more often than not that they are in fact very accurate.
I later switched the the Vltor A5 and again 100% no issues. Have you considered using a Springco spring? If not, I would.
Sounds like excessive bolt speed. That XM193 is loaded way too hot.
Odd that it’ll lock back on lighter buffers occasionally though. Could be a stiff Bolt catch plunger spring too. I fought that on one of my 11.5 SBRs. Bolt catch should be fluffy. Any stiffness at all on an SBR and it can be unreliable at lock back.