Thread: BSA 12 15 TO .22 HORNET CONVERSION

Originally Posted by akaroa1

@gundoc by fitting the hardened bush you didn't need to re harden the whole block when finished ?

Correct, the blocks were only case-hardened anyway. Once annealed, reassemble into the closed position and drop a hardened centre-pointed rod down the bore to mark the exact centre of the firing pin hole, then bore and thread it square to the breech face. The bushing should have a 1.5 - 1.8mm hole for the firing pin and two stub holes for a tightening key.