I did see one colt from the bad days of the mid-80's that had the ramp in the frame cut too deep, so the edge of the barrel ramp was actually hanging out in space creating a step the bullet nose had to negotiate. It would still run feed certain loads reliably, though - even some hollowpoints.
I'd suggest buying a copy of Jerry Kuhnhausen's book on tuning the 1911. It very neatly covers basic troubleshooting and customization - including the extractor fitting, which really is critical.
