Hi Sojerguy, Remember, the only way to get your dies to seat true, is to bottom them out on the shell holder before you tighten down the locking nut. On my 416 Rigby seating die, this won't work, as the seater is shorter. I don't know about the RCBS seating die. It may pay in the long run to buy a generic Hornady New Dimension sleeve seating die. Then you can always run a buckled case back into your RCBS seater, which will have enough clearance for a crimped bullet, if you just back off the seating stem. This 416 caliber seems to have a balance between inline seating, and support for the shoulders. One gives wonderful accuracy, and the other gives super reliability. But if you get superb accuracy with the RCBS dies, why bother going further? I found some canadian Rigby cases which were really soft, compared to the Federal Rigbys. So you may have to shop around for the right cases to reload with your new die set. Some, but not all of these 416 cal. boomers, are wickedly accurate. If you can just hold them down.