Man, that sure is nice! I was wondering: Would the plastic shrink or warp like that if it was used or out in the air more often? Also, the spec sheet in there said 7 round mag capacity. I thought they were all 8 round. Learn every day! Really a nice piece of jewelry you have scored!
jeffrefrig: These plastic grips were referred to by the factory as Coltwood and are notorious for shrinking. Odds are if the op takes them off the gun, he'll never be able to put them back on.
The original magazine capacity for the 1911 was 7 rounds. Some years back, somebody (Chip McCormack??) figured out how to redesign the follower so that you could get 8 rounds in it. So 8 has been pretty much standard since then.
Hot, near boiling water, let the grips set in it for a minute or so,,then they are pliable enough to stretch them to fit back on the frame over the screw bushings if they have shrunk over time.
The amt you can stretch them is limited however and some are just beyond that and you will end up pulling the panel apart like a piece of old taffy!