The old screw was broken off in the hole for many years. We got it out, which wasn't easy.
Threads fine, size fine, except it doesn't quite go down in far enough, it's a bit proud of the breechblock and thus the block won't go into the receiver.
I carefully installed and removed and installed and torqued it down as much as I dared.
Sadly I think I'm going to have to grind a bit off top of the new screw...hate doing it.
