TargetTalk

If you are going to drill out the head of the allen bolt, this is best done on a vertical mill or at least a really good drill press. You want good control of both the workpiece as well as the drill. On a vertical mill you would simply use a 4-flute end mill, the same diameter, or marginally larger, as the head of the bolt. In either case, mill or drill press, use a very slow speed. Make sure the gun/barrel is well supported and clamped.

Thanks for all the advise. Man it was stuck. I used the dremel and cut a slot like advised. Wouldn't budge. So I got bawlsy and drilled it out. That sight riser is toast, but got it off with no damage to the gun.

Do not drill unless you are certain you have the equipment and skill to dill the vertical center. Leave that for the gunsmith. You may want to sacrifice one allen wrench and use JB weld to glue it into the remains of the screw head or find some industrial grade of loctite or other adhesive.

Clean both surfaces with a grease/oil cleaner remover to insure a solid bond.

Good luck

disregard, I saw you got it. Congrats!