Just remembered that the other 1911 with the Wilson grip piece was my SA RO.Discovered that they fit pretty well a few,, not so well on others, and not at all on some. I put the SS one on my early 80's made Springfield Govt. model, it fit very well, the blue one is on my STI Spartan V , ( also a Govt. mode).. It was difficult to get it to stay on the STI, , ended up using rubber cement to the front strap, & then squeezing it around the frame, to get enough of the edges of the piece to fit under the G-10 grips I have on it
The problem is the Wilson piece is just a bit too short to fit under the grip panels, that are supposed to hold it on the pistol. If the edges were 1/8" longer, they'd fit better. If my memory is correct, when I tried it on a few Colts, they wouldn't fit at all. Frame shape, beneath the trigger guard is too wide, on my Delta & Combat Commander.
So far, all of those frames allow for proper fit/wrap around of the small tab, under the stocks.
I don't think I have any other 1911's that aren't already checkered on the front strap. So I may never find a frame that it will not work on.