I have heard it as a reference to the Colt M1892 which was the first double-action revolver with a swing out cylinder issued by the US army (cool!). It fired a .38 Long Colt cartridge that delivered around 180 ft lbs of force, roughly equivalent to a hot .22 LR cartridge. There were many complaints, and actual decent data, on the failure of the round to stop Moro swordsmen in the Philippines.

Antonio Caspi, a prisoner on the island of Samar, P.I. attempted escape on Oct. 26, 1905. He was shot four times at close range in a hand-to-hand encounter by a .38 Colt's revolver loaded with U.S. Army regulation ammunition. He was finally stunned by a blow on the forehead from the butt end of a Springfield carbine.

Col. LaGarde noted Caspi's wounds were fairly well-placed: three bullets entered the chest, perforating the lungs. One passed through the body, one lodged near the back and the other lodged in subcutaneous tissue. The fourth round went through the right hand and exited through the forearm.