You could get a flat stick... paint stirrer? and wrap fine grit sandpaper around it and then try to sand down any protrusions in the magazine well. Polymer isn't like steel and can vary with the temperature or deform a bit after being molded and released from the mold.
A dry lubricant can help, too, but I would try to sand down any irregularities or obstructions to give the magazines more clearance.
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".