I'd strip it down andclean it real good, look for a burr somewhere, or broken/bent partthen try it again.......

Sometimes all it takes is a lil' piece of junk to stop things up.

Had a piece of bore mop come off in the lug recess in a bolt rifle not too long ago, I use a .410 bore mop to clean certain rifle chambers. The bolt wouldn't close all the way and the piece of bore mop couldn't be seen and was a PITA to get out..........