If it's going to come out (some don't), try a large punch and a
couple good smacks with a heavy hammer from the side, if it
doesn't move in two or three hits, it most likely won't.  Yeah I
need it for an S12, I got one of the first Chaos extended rails
and mounted it to the rear of that (had to thin it down to fit
rail groove) with a bead up front, well the first gen long rails
weren't made right and you couldn't field strip it with it on.
So that was a waste of money & time.