I'm a Forster seater guy myself, but I've been known to slum RCBS. The problem with all the ideas so far it that backing off the RCBS to prevent crimping does nothing to square up the die. You want the case/die/seating stem to be co-linear. The problem is that the case isn't really supported by the sides of the seating side, so there is slop. I like the square up this type of die with a flat washer, then set the lock ring.
