OK, have a new Proof Research 7mm RM barrel that I just screwed onto my 110 action (was a LR Hunter in 25-06) fixed bolt face etc....

I have never headspaced a cartridge off the belt before. And I don't have any fired brass to try and headspace off the shoulder. Besides, i'm not sure that is a good idea for first firings of new brass anyhow....

So I headspaced off the belt, with about .002" excess. This is less than the SAAMI specs show in variation for the 7RM, so I think its OK. 2 layers of scotch tape will not close. One closes reluctantly. Zero closes like butter.

Here's the question: I typically load virgin rimless brass with a bullet seated into the rifling. This assures that the cartridge base is pushed back up against the bolt face. That in turn means that there will be little or no case body stretch and the shoulder will be blown forward. Thereafter, I neck size, with the occassional body bump back .002" if the brass is getting too hard to chamber.

Should I do the same thing with the belted magnum brass? Essentially attempt to make the belt superfluous? I plan to neck size my 7RM as well, treat it like any other brass that I keep the shoulder the same to avoid case stretch over time.....



Thanks in advance.......