The .38 Super is dimensionally identical to the .38 ACP of 1900. The .38 ACP fired a 130-grain bullet at 1,100 fps. The .38 Super was a sensation, noted for its high velocity of 1300 fps and nine fast shots. Colt upped the power of the cartridge but used the same length cartridge case and chambered the .38 Super in the 1911 when it dropped production of the .38 ACP pistols. At the time, you had to know not to fire a .38 Super in older Colt 1903 pistols.