Criterion is an offshoot of Kreiger. They'd need a non-standard tap for the rear sight screw holes too, not a problem for people used to dealing in machine tools. I tried to add to the post, but you have to be approved first. I'll certainly keep an eye on the thread, tired of buying .303 Britishicon bullets and sizing my cast bullets oversized for my .310 groove diameter barrels. The KCA forum is back up, I stop by so little I didn't even know it was down.