About once a magazine the bolt fails to travel rearward farther than pictured and is jammed tight - can’t rack it back and light/medium motoring doesn’t get it to go forward. It’s before the ejector has a chance to kick out the empty brass which is still being held by the extractor. I can only get the bolt to release by removing the bottom take down pin and allowing the lower housing to relieve pressure on the bolt/carrier.
It can be recreated manually by pushing down on the cocking lever while racking - and you can feel the bolt binding on something.
This was less frequent with my Franklin binary, more frequent when trying out a buddy’s RareBreed FRT, and minimal (but not zero) with the stock trigger pack. Probably have around 1k rounds in normal semi; 2-300 via binary; problem got acutely worse with FRT.
Am I looking at tolerance stacking? Should I try a new lower housing? Change back to 100* locking piece? Other ideas?
Gun deets:
PTR9kt
80* locking piece
Almost exclusively shot suppressed with 147gr (various loads - haven’t noticed a difference with any)
SiCo Spectre via tri-lug
Fresh extractor spring (<200 rounds)
Fresh recoil spring (<200 rounds)
Help please!