The basic function of the gauge is the same as the standard gauge. If you drop a round in, it should drop in freely, and the top of the case should sit somewhere above the bottom step and below the top step on the face of the gauge. If it is somewhere in that range, it should fit into your firing chamber without any issue. The patented slot down the side of the gauge allows you to check that everything is seating properly into the chamber. So you can visually inspect the cartridge and see that everything fits in the chamber the way it should.
