06-16-2018, 11:03 PM
Buy a round head brass machine screw, chuck it up in a drill, apply some lapping compound and go to town on your bore and it will do a nice job of lapping in a decent crown. From what I understand the closer in diameter the screw head is to the bore a better crown will result since the lap angle won't diverge much from the bore.
I'll be yer Huckleberry.

