.38 ACP [SEP] designer
.38 ACP
The .38 ACP (Automatic Colt Pistol) also known as the .38 Auto was introduced at the turn of the 20th century for the John Browning-designed Colt M1900. It was first used in Colt's Model 1897 prototype, which he did not produce. The metric designation for the round is "9×23 mm SR" (Semi Rimmed) (not to be confused with the later 9×23mm Winchester).
History.
Initial loadings of this cartridge were quite powerful. Reported ballistics for the first commercial
was ballistically similar to the .38 ACP but utilized a smaller case and higher pressures.
Browning himself was not done with 9mm cartridges and would soon introduce the 9mm Browning Long in 1903 and the .380 ACP in 1908.
.38 Super.
.38 Super was introduced in the late 1920s as a higher pressure loading of the .38 ACP. Even though .38 ACP and .38 Super are the same size, it is dangerous to use the more powerful .38 Super ammunition in a firearm intended for .38 ACP, as firearm