I don't have a 1911 but it should still apply,
I bought a bunch of these when they were available:
http://shop.ehobbyasia.com/nine-ball...-gbb-2pcs.html
Really helped freshen up the old mags. Shots feel alot more crisp and I even gained a bit of FPS.
Having said that, keeping the mags warm and your firing style (like Jordan said) seems to help me out the most.
I usually hold the mags in my arm-pits in staging.