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The SIG Sauer P320 (9mm) is a modern striker-fired handgun that has redefined what shooters expect from a duty or defensive pistol. Its modular design, excellent trigger, and proven reliability led to its adoption by the U.S. Army as the M17, replacing the long-serving Beretta M9. Today, the P320 platform continues to grow in popularity among military, law-enforcement, and civilian shooters worldwide.
Introduced in 2014, the SIG P320 broke new ground by featuring a serialized **fire control unit (FCU)** that serves as the legally regulated firearm component. This allows the user to change grip modules, slides, barrels, and calibers on one serialized FCU—making it one of the most versatile platforms on the market.
In 2017, the U.S. Army selected the P320-based M17 (full-size) and M18 (compact) pistols as the official sidearms for the U.S. Armed Forces, validating the design’s durability and combat-ready performance.
| Specification | P320 Full-Size / M17 |
|---|---|
| Caliber | 9×19 mm |
| Action | Striker-fired, single-action-only |
| Barrel Length | 4.7″ (M17 & P320 Full-Size), 3.9″ (Compact), 3.6″ (Sub-Compact) |
| Overall Length | 8.0″ (Full-Size) |
| Height | 5.5″ (w/ standard mag) |
| Width | 1.3″ |
| Weight (unloaded) | ~29.6 oz (M17) |
| Magazine Capacity | 17-round standard; optional 21-round extended mags |
| Frame / Grip | Polymer grip module (various sizes available) |
| Trigger | ~4.5–5 lb consistent pull with clean break |
| Optics Ready | M17 & most P320 variants are optics-cut for RMR / DeltaPoint Pro / Holosun 507C |
| Sights | Standard SIGLite night sights; M17 has removable rear sight plate |
| Finish | PVD-coated stainless-steel slide; coyote tan finish on M17 / M18 |
The serialized FCU makes it simple to switch between full-size, compact, and even competition-grade configurations without buying a whole new pistol. This level of modularity sets the P320 apart from most rivals.
The P320’s striker-fired trigger offers a crisp ~4.5–5 lb pull with a short reset. Upgraded flat-faced triggers on X-Series models improve control for precision shooting and faster follow-ups.
Modern P320 variants and the M17 ship with factory optic cuts. Red-dot sights have become standard for duty and competitive shooting, and the P320’s slide accommodates popular footprints like the RMR, DPP, and Holosun 507C.
The M17/M18 endured extensive U.S. military testing, including drop safety fixes, and emerged as a robust platform for high-volume use. This track record translates into confidence for civilian and law-enforcement shooters.
The interchangeable grip modules let users tailor size, grip texture, and color. Combined with a low bore axis and high grip cut, the P320 offers excellent recoil control and shooting comfort.
The P320’s barrel-to-slide lockup and clean trigger contribute to excellent out-of-the-box accuracy. Many shooters report consistent performance in both slow-fire and rapid-fire drills.
The low bore axis and full-size frame help mitigate muzzle rise, especially when using 21-round mags for extra weight. Upgraded X-Series triggers and Spectre Comp models further flatten recoil for faster splits.
Field use by U.S. military forces demonstrates the P320/M17’s ability to function with various 9mm loads under harsh conditions. Routine maintenance ensures it keeps running reliably for tens of thousands of rounds.
The P320’s modular FCU makes it one of the easiest modern pistols to maintain. Field-stripping does not require a trigger pull; rotate the takedown lever to release the slide. Routine cleaning of the slide, barrel, and FCU plus periodic lubrication keeps the gun reliable over the long haul.
The SIG Sauer P320 / M17 (9mm) combines modern ergonomics, combat-tested reliability, and unmatched modularity. Its military adoption proves it can withstand rigorous field use, while its interchangeable configurations make it adaptable for civilian defense, competition, and training. For anyone looking for a versatile striker-fired handgun with proven performance, the P320 / M17 is one of the strongest choices on the market today.
Disclaimer: Always follow all applicable laws, regulations, and safe-handling practices when purchasing or using pistols. This article is for informational purposes only.
