Failure to go into battery

[ecosystem3]

Do not take anything apart until you make sure your chamber isn't short and your jamming.

Drop a round of ppu120 in the chamber, muzzle down bcg locked back. Make sure there is no mag in the mag well.

Hit the bolt release and let the bcg slam home then see how it acts when trying to extract the round.

Tried this a few times. The BCG is jammed in the forward position and requires a mallet to disengage. Once disengaged, the ppu120 falls out via gravity. There is some marking on the rim of the casing but nothing on the throat or bullet.