Hello, I got a set of RCBS SB (short Base) 223 dies on a trade. I have read that the SB dies are for semi's,pumps and full auto's and not recomended for bolt guns. They say that they push the neck down slightly and size differently then the FL dies. I have compared them with my FL dies and don't seem to see or find any measurment difference and the brass fits in my bolt gun the same?? Does anybody know what the difference is and can they be used with a bolt gun?? Thanks. Kevin.