Once fired brass from different rifle

[rsnell]

Full length size the brass and try it. If it does not chamber, you will need a Willis die.

 

[44-40]

RCBS used to make small base dies for 300 Win Mag to size belted cases in 300 WM for auto loading rifles like the Browning BAR. They make one in 7mm mag too. Also try a different die, borrowed from a shooting friend. They are not all the same... just had a 308 that was difficult to chamber, and have 6 308 dies from over the years ...tried several including
A redding body die, then ran the same case through the Hornady die it took more pressure to manually size it and it chambered wonderfully.

 

[SSG Graybush]

Question... With brass (and everything else) being hard to find. I've seen some once fired brass for sale and am thinking of picking some up. Brass is advertised as fired for testing, tumbled and inspected for damage.
In my experience once fired brass (neck sized) out of my gun gives me supreme accuracy but I question how different it would be using brass from a different rifle and only neck sizing. This is for a 7mm Rem Mag... so belted case.
Thoughts? Experience?
Thanks

Only Nk sizing is wrong period. Bumping the shoulder back 1.5 to 2 thou from fired will give as good or better accuracy. Watch neck sizing is stupid by Eric Cortina. But once fired brass that's not from your rifle should be at least FL sized first. Or it may not chamber.