Because of work hardening from repeated firing and sizing, the die setting required to produce a given amount of shoulder bump changes. Shooters who use a large number of cases in a situation where the number of firing/sizing cycles per case is relatively small may not be up to speed on this. Any time you size a batch of cases, the amount of shoulder bump should be checked, to avoid wasted effort, and difficulty in the field, or at a match. The real area of advantage of the Lock-N-Load comes when alternating between sizing and seating, on a single stage press, when doing load testing at the range. In those situations, it is too easy to loose a die setting without this feature. That is why I set up my Rockchucker with a Lock-n-load adapter bushing. I will still do die setup measurements, but once the dies are set for a particular loading session, I can alternate between them, confident that the settings will be maintained. I should add that the usual situation that has this press at the range is when I am helping friends work up loads for their big game hunting rifles. For everything else, I simply use my Harrell's turret press, which is much more portable, or my Combo-Press for small calibers for which I have arbor press type seaters.
