It is a method of correlating relative velocities of shotshells loaded with smokeless propellant to shotshells loaded with black powder. The reference black powder load chosen was a 3-dram charge of black powder, with 1 1/8 oz. of shot and a velocity of 1200 fps. Therefore, a 3-dram equivalent load using smokeless powder would be with 1 1/8 oz. of shot having a velocity of 1200 fps. or 1 1/4 oz. of shot and a velocity of 1165 fps. A 3 1/4 dram equivalent load might have 1 1/8 oz. of shot and a velocity of 1255 fps.
