Today I was running a round into my P99 (9mm, AA, all German) and the slide did not close all the way (1/16" open), then I released the mag, and tried to eject the live round and the slide was stuck. Only by greatly increasing the force to retract did I get the round clear. It happened consistently with several different 10 round mags regardless of the number of round in the mag. Something internal is out of line but what? Where do I start to debug this? Your advice please.