Trisha Shetty (Editor)

SIG Sauer P320

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Type  Semi-automatic pistol
In service  2014–present
Place of origin  United States
SIG Sauer P320
Designer  Adrian Thomele, Thomas Metzger, Michael Mayerl, Ethan Lessard
Manufacturer  SIG Sauer GmbH, Eckernförde, Germany; SIG Sauer Inc., Exeter, NH, United States
Variants  Full-size, Carry, Compact, and Subcompact

The SIG Sauer P320 is a semi-automatic pistol made by SIG Sauer of Exeter, New Hampshire and SIG Sauer of Eckernförde, Germany. The SIG Sauer P320 can be chambered in 9×19mm Parabellum, .357 SIG, .40 S&W, and .45 ACP. The P320 chambered in 9×19mm Parabellum was introduced in the North American market on January 15, 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 January 19, 2017, it was announced that the SIG Sauer P320 had won the United States Military XM17 Modular Handgun System competition, with a specialized version to become the new M17 pistol.


Operating mechanism

Like other SIG Sauer pistols, the P320 pistol is a short recoil operated, locked breech pistol. It uses the typical SIG Sauer cam-operated barrel, which locks into the ejection port on the slide.


A key feature of the pistol is its modular design. The main module of the P320 is an internal stainless steel frame fire control unit, which consists of the integrated fire control group (trigger, and all necessary linkage and springs), ambidextrous slide release (one on each side of the pistol), ejector and four slide rails. This steel receiver unit is used in every P320 grip module, top end, and chambering combination and is inserted into the grip frame module and held in place by the axis pin of the disassembly lever. The firearm's serial number is on the fire control unit instead of the grip module. The fire control unit allows the operator to interchange differently-sized slide assembly or top end modules and polymer grip frame modules and trigger shoes and (limited) chambering conversions to adapt the gun to the individual user and address different needs.

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.

The full-size, carry and compact grip modules feature an integral Picatinny rail mounting-bracket at the lower forward edge of the module to allow the mounting of laser sights, tactical lights, and other accessories.

Modular options

The P320 pistol is offered in three glass-reinforced polymer grip module sizes—small, medium, and large — in each of the full-sized, carry, compact, and subcompact P320 variants. The pistol top ends also come in full-sized, compact, and subcompact variants that will fit the correspondingly sized grip modules. Every chambering can be converted by the user with a caliber exchange kit. The 9×19mm Parabellum, .40 S&W, and .357 SIG chamberings share their polymer grip frame modules and this offers the possibility to interchange these three chamberings by swapping the top end — consisting of the slide, recoil spring assembly, barrel and the box magazine. Due to the significantly larger external dimensions of the .45 ACP cartridge compared to the other P320 chambering options, the .45 ACP chambering uses slightly wider .45 ACP–specific polymer grip modules with an enlarged magazine well. The firearm's "fire control group", which contains the only "registered" part of the firearm, is also slightly different to accommodate the enlarged magazine well.

The manufacturer offers caliber exchange kits or Caliber X-Change kits consisting of a slide, recoil assembly, barrel, box magazine and grip module in the varying frame sizes, grip module sizes and chambering variants in which the P320 pistol is offered. These kits enable a user to switch between the various P320 configurations without the use of tools.


The standard P320 has no manual safeties, promoting instant readiness. Instead of manual safeties, an automated firing pin safety ensures safe carrying of the weapon while preventing accidental discharges if the gun is dropped or roughly handled. The Modular Handgun System (MHS) or M17 version of the P320 has an ambidextrous thumb safety.

Trigger system

The trigger is a pretensioned striker DAO trigger system. The trigger system has a pull weight of about 28.95 N, 5.5 lbf

The P320 trigger is available in standard (solid) and tabbed (with trigger safety).


The P320 is available with a 120 mm (4.7 in), 98 mm (3.9 in), or 91 mm (3.6 in) barrel depending on the size (full-sized, carry/compact or sub-compact respectively).

Ammunition feeding

The pistol feeds from metal detachable box magazines with a six- to twenty-one-round magazine capacity, depending on chambering and pistol size.


The P320 comes with three-dot combat-type iron sights of which the front sight element can be drifted to the left or right in its dovetail to adjust for windage. There are three rear sight heights and six front sight heights available to adjust for elevation. Self-luminous tritium-powered SIGLITE Night Sights in differing heights are optional. SIGLITE night sights are optional, but come standard in exchange kits.

The SIG Sauer Romeo1 sight is supplied on the RX Full and RX Compact versions of the P320.


The factory accessories consist of spare magazines, caliber exchange kits, a short, reduced-reach trigger shoe, handgun holsters, and the STL-900L Tactical Light/Laser unit.

Modular Handgun System

Designed to meet the requirements for the XM17 Modular Handgun System competition.

Modifications include:

  • Slide cut out to facilitate the addition of a reflex sight
  • Ambidextrous thumb safety
  • Loaded chamber indicator
  • Improved slide sub-assembly to capture small components when disassembled
  • Improved trigger "mud flap" to prevent foreign debris from entering the pistol action
  • 117 mm barrel length in full size, 99 mm in compact
  • chambered in 9×19mm Parabellum (can be adapted to fire larger calibers like .357 SIG and .40 S&W)
  • Pistols chambered in 9mm can feature a 17-round magazine in standard with optional 21-round extended magazines available.
  • On January 19, 2017, it was announced that the SIG Sauer P320 MHS variant had won the United States Military's Modular Handgun System trials. The P320 will be known as the M17 in U.S. Military service. Though the pistol will remain chambered in 9×19mm rather than a larger caliber, the contract allows the Army and other services to procure Sig Sauer’s proposed XM1152 Full Metal Jacket and XM1153 Special Purpose ammunition.


    Rob Curtis at GearScout praised the P320's smooth operation and good balance, calling it "immensely controllable", but noted a problem with the slide lock in both test units he tried.


  •  Thailand: Royal Thai Police; Purchase of 152,468 SIG Sauer P320 pistols is approved.
  •  United States:
  • United States Army - On January 19th, 2017, the P320 was chosen to replace the Beretta M9 as its main service pistol in response to the request for a Modular Handgun System (MHS) also known as XM17.
  • Hawaii Department of Public Safety.
  • Oklahoma Highway Patrol.
  • Pasco County Sheriff's Office.
  • City of Columbia, SC Police Department
  • References

    SIG Sauer P320 Wikipedia