If you do a lot of reloading different calibers you need a couple sets of these.
Handy Shim Sets for Sizing Dies — Quickly Adjust Shoulder Bump « Daily Bulletin
When your cases become hard to extract, or you feel a stiff bolt lift when removing a cartridge, it's probably time to full-length size your cases, and bump the shoulder back. Short-range benchrest shooters, running high pressures, typically full-length size every load cycle, bumping the...
bulletin.accurateshooter.com