Hmm.. kind of a loaded question. Any part can theoretically rattle.
But if it is general looseness of the 1911, can be slide to frame fit, bushing fit, loose lugs, etc. Not a do-it-yourself project, IMO, you can munge up your gun pretty good.
If you're really interested in the subtleties, I'd recommend Kuhnhausen's (sp?) books on the 1911 - you'll really start to appreciate what the top-tier 1911 smiths can do.