I have a Para p12 and the slide stop hole is a little sloppy. I just noticed it and have not measured it yet. I searched around here and other places and got the impression that once it is to bad, it becomes a paper weight. Welding and re milling was repeatedly shot down for the loss of temper in a critical area.
I was thinking that one could press fit a sleeve in the frame(.200 ID and .250 OD for example) and then re mill the barrel lug notch. Let me know if this would work or any other way that would work.