For some inexplicable reason, the firearm industry is enamored with oddball fastener sizes. I've been working on an XP-100, a Wh***'s nightmare of firearm engineering. It's no wonder they're not made anymore.
I have a buddy who has made a few 1/4-25 action screws. He was happy his lathe has 25 tpi. Mine doesn't. it has 23 and 27, but no 25....
