Originally Posted by 7mmSendaro
I'll have to watch that in the future. I have not loaded most of my brass more than 2 or 3 reloads with neck sizing yet except the 22-250. I'll keep an eye on it. Thanks.
The break action is simply not as solid as a bolt action with its locking lugs. What happens is, as the action flexes ever so slightly upon firing, the hot brass of the case stretches to fill the void, allowing the case to exceed the head space of the cold chamber. If the case is already at or near the max head space dimension, while it may still be loadable in the chamber due to the caming effect of the action closing, after firing the case is jamed in the chamber and you will not be able to open the action. Therefore you will have to drive the pivot pin out of the action in order to open it and extract your case. You certainly do not want to have to do this on a hunt as your single shot rifle will truely become a single shot! Therefore, after firing a case, especially if it is a hot load, it is best (or necessary) to bump the shoulder back slightly each time.