Short primers backing up and leaving a mess. Pretty typical.

On this V2 i used Gun Shield on the frame and barrel for protection.
http://www.youtube.com/user/frontier.../0/u6klwwA56DE

Back your firing pin bushing out so the slots are pointed up and down VS horizontal.

In order to get that nasty fouling off i always had to use 0000 steel wool soaked in oil. Lightly go at the fouling until its decently clean.