Mine seldom jams but when it does, it's always a twofer in the receiver.
Like the fired case doesn't pop out right and the new round kinda goes half in the chamber with the fired case stuck over to the left side.
It jammed CONSISTENTLY with truncated bullets but with any rounding of the bullet nose, it runs great.
HOWEVER.... looking at the last cussfest, it APPEARED that tapering the inside edge of the TOP of the port and lowering the BOTTOM edge would create a lot more room for the commotion it needs. Followed by nice polish.
Being careful to keep the bolt fully contained and not go wild with the grinder.
Whatcha think?
Probly won't do it as it is so infrequent, but just musing a bit.