Originally Posted by
rsterne
I initially drilled the .250" counterbore in the .224 barrel with a stub drill.... turned out fine, nicely centered, (I didn't go very deep) but the (118*?) shoulder was too steep and with the tightness of the chamber it was actually shaving the bullet when I pushed it in.... Soooooooo, I changed to using a center drill with a 60* taper, I had one that was 1/4" OD.... I drilled in until the taper stopped about 0.030" from the barrel port, and then polished the .250" section and the taper with 400 grit, paying particular attention to where the taper met the .224 chamber to smooth and round the edge so there was nothing to shave the bullet.... I think you might want to polish the chamber a bit more if your barrel is as tight as mine.... When I push a bullet in, it polishes the driving bands just going through the section aft of the barrel port, let alone in front of it.... It's pretty difficult to load, actually, requiring quite a lot of force to seat the bullet, especially by the time you get the base flush with the front of the barrel port.... My bolt probe is actually leaving a dent in the base of the bullet, that's how tight it is....
Bob