SIG Sauer P320 Full Size
SIG Sauer · Pistol · In Production · 2014
Also known as: P320, P320 Nitron Full Size, P320 Full
Overview
The SIG Sauer P320 Full Size is a modular, striker-fired, semi-automatic pistol that revolutionized the handgun market with its unique serialized fire control unit design. Introduced in 2014, the P320 was the first commercially successful modular handgun, allowing users to swap calibers, grip sizes, and slide lengths around a single serialized stainless steel fire control unit chassis. The full-size variant features a 119mm barrel, 203mm overall length, and a 17+1 capacity in 9mm. Weighing 836 grams unloaded with a polymer grip module and Nitron-finished stainless steel slide, the P320 Full Size delivers a smooth 29-newton striker-fired trigger pull with a clean break and short reset. The pistol includes an M1913 accessory rail, three-dot contrast sights, and a three-point takedown system that requires the magazine to be removed and the slide locked back before disassembly. Available in three interchangeable grip frame sizes (small, medium, large), the P320 allows shooters to customize the ergonomics without requiring an FFL transfer. The P320 platform won the U.S. Army's Modular Handgun System competition in 2017, with the military variants designated M17 (full-size) and M18 (compact), replacing the Beretta M9 as the standard-issue sidearm across all branches of the U.S. military.
Specifications
| Weight (empty) | 836 g (29.5 oz) |
| Weight (loaded) | 1042 g (36.8 oz) |
| Overall Length | 203 mm (7.99") |
| Barrel Length | 119 mm (4.69") |
| Height | 140 mm (5.51") |
| Width | 33 mm (1.30") |
| Sight Radius | 168 mm (6.61") |
| Action Type | Short Recoil |
| Firing Mechanism | Striker Fired |
| Trigger Type | Single Action |
| Trigger Pull | 29 N (6.5 lbf) |
| Magazine Capacity | 17 rounds |
| Magazine Type | Detachable Box |
| Muzzle Velocity | 375 m/s (1230 fps) |
| Muzzle Energy | 524 J (386 ft·lbf) |
| Effective Range | 50 m (55 yd) |
| Maximum Range | 1800 m (1968 yd) |
| Barrel Rifling | Right Hand |
| Rifling Twist | 254 mm (10.00") |
| Number of Grooves | 6 |
| Frame Material | Polymer |
| Slide Material | Stainless Steel |
| Barrel Material | Carbon Steel |
| Finish | Nitron |
Calibers
- 9x19mm Parabellum · primary · 9mm NATO — also known as 9mm Luger, 9mm NATO, 9x19mm
Features
- Firing modes: Semi Automatic
- Feed systems: Detachable Box Magazine
- Safety mechanisms: Striker Safety, Disconnect Safety
- Features: Modular Fire Control Unit, Modular Grip System, Accessory Rail, Contrast Sights, Interchangeable Grip Sizes, Reversible Mag Release, Nitron Finish, Three Point Takedown
Variants
- SIG Sauer P320 M17 — Military Contract
- SIG Sauer P320 M18 — Compact Military
- SIG Sauer P320 X-Carry — Carry
- SIG Sauer P320 X-Compact — Compact
- SIG Sauer P320 X-Five — Competition
- SIG Sauer P320 XFull Size — Enhanced
- SIG Sauer P320 Compact — Compact
- SIG Sauer P320 Subcompact — Subcompact
- SIG Sauer P320 Carry — Carry
- SIG Sauer P320 AXG — Premium
- SIG Sauer P320 Spectre — Premium
Service history
Operators
- United States Army · adopted 2017 · as M17/M18
- Danish Armed Forces · adopted 2018 · as P320 X-Carry
- Mexican National Guard · adopted 2019 · as P320
- Canadian Armed Forces · adopted 2022 · as C22
- Australian Defence Force · adopted 2022 · as F9
- Swiss Armed Forces · adopted 2024 · as P320 X-Carry Pro
Conflicts
- War in Afghanistan (2001-2021)
- Operation Inherent Resolve (2014-present)
Production
Production years: 2014-present
One of the best-selling pistol platforms in the world; military procurement alone exceeds 421,000 M17/M18 units across U.S. forces, with millions more sold commercially
Origin
Country of origin: United States
Designer: Ethan Lessard
Notes
The P320 was designed by SIG Sauer engineer Ethan Lessard and introduced at the 2014 SHOT Show. Its key innovation is the serialized fire control unit (FCU), a removable stainless steel chassis that houses the trigger, sear, and striker mechanism. This means the FCU is the legal firearm, while the grip module, slide, and barrel are all unregulated accessories that can be purchased and swapped freely. The original P320 Full Size does not include a manual external safety, relying instead on the internal striker safety and disconnect safety. Military M17/M18 variants add an ambidextrous thumb safety per military requirements. The P320 family has expanded into numerous configurations including the X-Five competition model, X-Carry, X-Compact, AXG (alloy grip), Spectre, and XTEN (10mm). The platform is also available in .40 S&W, .357 SIG, and .45 ACP, though 9mm is by far the most popular chambering. Early P320 models faced scrutiny over drop-safety concerns, which SIG addressed with a voluntary upgrade program in 2017 that added a lighter trigger, a smaller disconnect, and a modified sear.
Background
The P320 ended the 32-year reign of the Beretta M9 as the U.S. military's standard sidearm when it won the Modular Handgun System competition in 2017. Its revolutionary fire control unit concept means you can legally buy a complete P320 pistol, remove the FCU, drop it into a different grip module and slide assembly, and have what is functionally a different gun - all without any regulatory paperwork. This modularity has spawned an entire aftermarket ecosystem of custom FCU builds.