The Glock 21 is the full-size .45 ACP variant of the Glock platform, offering the largest frame in the standard Glock lineup. Despite its larger caliber and increased cartridge size, the G21 retains the Glock operating system and shares many components with the 9mm and .40 S&W variants. Adopted by some US police departments and military units preferring .45 ACP. Type: Pistol Action: Semi-Automatic Caliber: .45 ACP Capacity: 13 Year introduced: 1990, Austria Weight: 26.28 oz Overall length: 8.22" Status: Active Intended use: Law Enforcement, Civilian Defense