Blackout subsonics not cycling
Trying to get Rem 220 subs to cycle. Ejects but won't pick up next round and closes on empty chamber.
Using a 16" new ER Shaw barrel with carbine length system on a Bushmaster upper and lower, A2 front sight base, and BCM M16 carrier with standard buffer spring. Tried both carbine and H2 buffers.
Standard buffer was a no-go but got it to cycle 2 rounds only a couple times with the H2. Still won't hold open on last shot using new Pmags. Running the BCG pretty wet and using a YHM 7.62 Phantom on brake QD mount. Cycles just fine with supersonics.
I'm leaning toward enlarging the gas ports (until I can get an SBR stamp) but any other suggestions??