is .45 auto and .45 acp the same
The .45 ACP (Automatic Colt Pistol), or .45 Auto (11.43×23mm) is a handgun cartridge designed by John Browning in 1905, for use in his prototype Colt semi-automatic pistol. After successful military trials, it was adopted as the standard chambering for Colt's M1911 pistol, being named .45 ACP.
.45 ACP