If you replace the brass grub screws with steel ones and place a piece of #4/3 lead shot under the grub screw, you will never have a lock ring move on you AGAIN!I have RCBS dies with the lcoks, but no matter how much i tighten them they would always move after tightening the die to the press rather tightly.
I do this on ALL of my lock rings and I can wrench my dies home and the lock rings NEVER MOVE ON THE DIE.
The lead shot compresses so tightly that it is difficult to move the ring after loosening the screw for adjustment, some manipulation with a wrench is required, but can be done by hand.
Cheers.