Welcome to the forum. Sometimes there is some interference or interaction like that causing peening or deformation that can be removed with a whet stone, file, or even sandpaper to stop the "mushrooming" from growing and hindering the action. Pictures would be helpful, but it sounds like the parts weren't perfectly machined and are trying to mate together during break-in, but may need some help to stop the interference.
The take down video can still be helpful with assembly/reassembly as the slide stop pin is easily inserted incorrectly. That part starts at about 4:30:
http://www.youtube.com/watch?feature...&v=G2cZgVg_SwA
Wynn
USAF Retired '88, NRA Life Member. Wife USAF Retired '96
Avatar: Wynn re-enlists his wife Desiree, circa 1988 Loring AFB, ME. 42nd BMW, Heavy (SAC) B-52G's
Frédéric Bastiat’s essay, The Law: http://mises.org/books/thelaw.pdf
Thomas Jefferson said
“A government big enough to give you everything you want, is strong enough to take everything you have.”
and
"Peace is that brief glorious moment in history when everybody stands around reloading".