The item at issue is an original 1861 Springfield ( Springfield Armory) lockplate that needs the bridle screw hole rethreaded( I bored out the the original broken off screw on a milling machine( no PB blaster/ gentle heat/screw extractor was moving that thing) so the threads are still in there and the dia of the hole is OK to rethread for an original screw).
The original screws are .182" major diameter and 26 tpi thread pitch; it's not really a true v form thread, more rounded, at least on the screws.
If I was a clod, I suppose one could do it with a 10-24 tap and force the screw in but that's not going to happen. Before I make a custon tap, I was wondering if anyone knows of a source of such a tap or has other ideas.
Note that it's a "fine" lockplate, not to be boogered
Thanks
AB
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