Quote Originally Posted by bigedp51 View Post
With the competition shell holder it allows the die to make hard contact with the shell holder with press cam over. This takes all the slop out of the press and thus more uniform shoulder location.

You can also pause at the top of the ram stroke for 4 or 5 seconds and this will greatly reduce brass spring back. The more the case neck and shoulder are work hardened the more spring back you will have that effects bullet grip and shoulder location.

The best part about the Redding competition shell holders is you never have to touch the die to adjust the amount of shoulder bump.
The Redding Competition shell holders should also be used in conjunction with the rifle you are loading the ammo for. Following Redding's instructions one starts with the largest number shell holder and after sizing checks for fit in the rifle chamber. (Ideally with a stripped bolt the first time) If the case doesn't fit well, and bolt closure is hard, use the next lowest number (.002" more "bump") and repeat until the case fits and the bolt closes "just right". Once this is done then that number shell holder can be used for all cases being sized for that rifle. When using a press that has a decent amount of "cam over" makes for exceptionally uniform case dimensions.

Remember that when sizing a case with any taper in it, different shoulder set backs also means different case dimensions all along the case wall, from shoulder to head.