I bought my first Sig this last week. Somewhere between round 10 and 15 the rear sight elevation screw went flying. It just refuses to go back in.

Is one hex wrench on one screw the all that’s needed to remove the sight? The slide has two holes for the sight mount. One is the hex screw and the other appears to be a locating pin. Is that correct?

M17 commercial sight plates have two screws, one of which is blocked by the extractor plunger. You have to remove the backplate, striker, and extractor plunger. X5 should be similar but I'm not sure.