According to cartridge drawings it should work "theoretically", with the 280 Rem being at 0.445" where the 7X57 shoulder is at 0.430", but then you have to factor in the size of the 7X57 chamber being reamed (is it generous - was it cut with a sharp reamer?) and the 280 Rem reamer dimensions. 0.015" isn't much to work with, so the 280 Rem AI would be a better bet. That said, I reamed a 300 Norma Mag chamber with a 300 Win Mag reamer knowing it was touch and go, and had a visible line where the old chmaber had been, but it didn't affect chambering, reloading or shooting.




















































