The Angstadt Arms UDP-45 is an AR-pistol chambered in .45 ACP with a 4.5-inch barrel, accepting Glock 21 magazines. It is among the most compact .45 ACP AR-format pistols in production, designed specifically as a suppressor host. Type: Pistol Action: Semi-Automatic Caliber: .45 ACP Capacity: 13 Year introduced: 2019, USA Weight: 52 oz Overall length: 18.5" Status: Active Intended use: Home Defense, Suppressor Host, Concealed Carry Pistol