In a trade .. I got a complete used caspian upper for a 45 acp 1911…. It does not fit , the slide will not even engage the rails on the complete 1911 firearm frame (also in 45acp ) I presently have. Both are 5 inch . I do not want to alter the frame as it already has a properly fitted slide.
Question…
Is it acceptable to modify just the “new” slide to fit the “old” frame.