30.06 50 cal 25mm eger
From my own collection: a .30-06 M2 ball round as used in the M1917/M1903/M1, the .50 cal BMG as used in the M2 machine gun, and a 25x137mm Bushmaster dummy. Keep in mind that the 28×199 as used by the 1.1-inch gun is about 2.45-inches longer. (Photo: Chris Eger)