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The .45 ACP Automatic Colt Pistol), also known as the .45 Auto by SAAMI, is a cartridge designed by John Browning in 1904, for use in his prototype Colt semi-automatic .45 pistol. The .45 ACP was eventually used in the M1911 pistol which was adopted by the United States Army. -
The .40 S&W cartridge was developed from the 10mm cartridge. It has the same diameter bullet and case, but is shorter overall. The .40 S&W was developed after the infamous “Miami Shootout” between FBI agents and two serial bank robbers where it took in excess of six 9mm rounds to incapacitate each bank robber.
