Back to the 360 2 1/4 and the 360 2/14 EXP. They are the same case but the non EXP rifles are of the BP era with slow twists and a 200ish grain bullet. The EXP proof rifles are more recent and have fast twists and are marked for a 300 grain bullet and 25 or 30 grains of CORDITE (not to be used in a rifle not proofed for it).