The SIG Sauer P320 is a modular design of semi-automatic pistol made by SIG Sauer, Inc. of Exeter, New Hampshire and SIG Sauer GmbH of Eckernförde, Germany. The SIG Sauer P320 can be chambered in 9×19mm Parabellum, .357 SIG, .40 S&W, and .45 ACP. The handguns made in 9mm, .357 SIG, and .40 S&W calibers can be easily converted from one to another.
The P320 chambered in 9×19mm Parabellum was introduced in the North American market on 15 January 2014, followed by the .45 ACP compact model at the SHOT Show in January 2015. The P320 is a further development of the SIG Sauer P250, utilizing a striker-fired mechanism in lieu of a double action only hammer system. On 19 January 2017, it was announced that a customized version of the SIG Sauer P320 had won the United States Army's XM17 Modular Handgun System (MHS) competition to replace the Beretta M9 as its main service pistol in response to the request for the full-sized model also known as the M17 and the carry-sized model also known as the M18.
The P320 was designed to be ambidextrous in handling, sporting an ambidextrous slide catch lever and user-reversible magazine catch. All other operating controls are designed so they can be operated from either side. The firearm can be field stripped with no tools. Additionally, the firearm can also be field stripped without depressing the trigger, an additional safety feature to prevent negligent discharge of the weapon.