Thread: Full length resizing 7mm Rem Mag problem

Originally Posted by grandpamac

Greetings Nick.m,
I suspect you are over sizing your cases. This is likely to happen if you set your die down hard on the shell holder. See Pommy's post about shoulder bumping above. Belted cases are tricky to resize. Serious reading is required.
Regards Grandpamac.

I would agree totally

With belted mags you need a comparator attachment for your digital calipers (such as the hornady system) to take the real fired shoulder to head (base) reading. That can be up to 6thou longer than factory/unfired i've found.
The main thing is that you want your reloads to fit slightly bumped but engaged at the shoulder. So take off .002". You don't want to knock it all the way back .006" or it will return to indexing off the belt (which is not so great).
Dont know about sharp edges tho sorry. I use imperial wax outside and graphite inside, have never had my shoulders come out sharp from rcbs, hornady, redding or forster. Lee, well lets just say i hate my 45-70 dies. Scratchy.

p.s This is where having access to a modern annealer will help. I can usually get the shoulders to within .0005" after induction annealing (amp)