I've been shooting Lee conical in my reproduction Remington New Model Army. The rebated base starts square and they shoot great.
I just recently bought the Lee 452-200rf mold and thought it would be great for the cap and ball revolver. I have read it is possible to size part of the base so it acts like the Lee conical designed for the cap and ball revolvers. It looks like I can get a .446 die, a gas check seating attachment, and back the pure lead boolets partially into the die to size the base to start square into the cylinder.
Anyone have any experience with this?