Thread: Full length resizing 7mm Rem Mag problem

Greetings again Nick.m,
I just had a quick read through the replies and noted that no one had mentioned the reason we avoid over sizing, especially in belted cases. When an over sized case is fired it gets shunted up the front of the chamber by a combination of the firing pin strike and the primer going off. As pressure builds the case stretches until the case base meets the bolt face. All this stretching occurs not far in front of the belt which thins the case at that point. After as little as three or so loads (depending on the amount of head space present) the case can crack when fired leaving the front half of the case in the chamber, something to be avoided. Sizing the cases just enough to chamber, minimum shoulder bump, largely prevents this.
It is not all beer and skittles however. The minimal sizing leaves a section of the case in front of the belt unsupported. Depending on the case make and rifle chamber, after a number of loads, this section of the case can stretch to the point that the case chambers hard, a problem that can persist even after full length resizing with the die hard down on the shell holder. There is a special die available to fix this should it occur. This problem does not occur with every rifle but can be hard to spot if you don't know about it.
Handloading is a permanent state of ongoing learning. Welcome.
Regards Grandpamac.