SEE is NOT a problem with single base fast pistol powder. Nor is case fill. Slower rifle powder can be a problem. There is a theory that small flash hole and light loads can allow the primer to be pushed out before the load ignites. It is a piston in a chamber with a small 'valve'. BO sub ammo doesn't use enlarged flash holes. You are not putting 5 gr. of Unique a 30/30 case!