small locking screw?
 

What is the size and tread of the small locking screws on the side of the frame?

The Galzan made replacement lock screws are 2-56. But the originals appear to be 2-54.

A galazan screw threads into my screw checker nicely, but an original goes in only a little before binding up a little. But judging by my thread pitch guage, both 56 or 54 look to be good matches as good as my eyes can see. But since an original binds in a 2-56 guage, that is why I say 2-54 for an original screw.