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SIG Sauer P320 M18 Pistol Review

Introduction of the SIG Sauer P320 M18 Pistol

Sig Sauer P320 M18 Review

Embarking on a journey into the realm of cutting-edge handguns, the SIG SAUER M18 emerges as a standout member of the revered P320 family. This comprehensive review delves into the key features, performance attributes, and overall impressions of the M18, while also drawing insightful comparisons with its predecessor, the M17.

The U.S. Army awarded Sig Sauer in 2017 a substantial $580 million contract to produce the next-generation service pistol, building upon the success of the P320 handgun. Triumphing over competitors like Glock Inc., FN America, and Beretta USA in the Modular Handgun System competition, Sig Sauer secured the 10-year agreement to supply the Army with both full-size and compact versions of their acclaimed pistol.

Expressing gratitude for the selection, Ron Cohen, CEO of Sig Sauer, stated at the SHOT Show in Las Vegas, “We are both humbled and proud that the P320 was selected by the U.S. Army as its weapon of choice.” The contract allows Sig Sauer to manufacture the firearms, known for their modularity and adaptability, at their facilities in New Hampshire.

The P320 boasts a modular design, featuring interchangeable grips and the ability to switch between multiple sizes and calibers, including 9mm, .357SIG, and .40S&W. Highlighting its versatility, Sig Sauer emphasizes, “From calibers, to pistol size, to the grip fit best suited for the shooter, the P320 is the most adaptable pistol available today.”

In confirming the Army’s choice, sources revealed that Sig Sauer had submitted both .40-caliber and 9mm pistols for consideration, with the Army ultimately opting for the 9mm version. This significant contract underscores Sig Sauer’s commitment to delivering a state-of-the-art, adaptable sidearm that meets the stringent requirements of the U.S. Army.

Military Purchases

The Air Force has slated an acquisition of 130,000 M18s, while the Navy has intentions to procure 60,000. Notably, the Marine Corps is set to acquire 35,000 MHS pistols, designating the M18 as the official sidearm of the Corps, as per SIG Sauer’s announcement.

Differences between the Civilian and Military Sig Sauser M18

One of the first difference you will see is the actual packaging. The military SIGs come in a plain paper box with foam

The Civilian SIG Sauer P320 M18 comes in a nice foam pistol case.

The civilian iteration of the P320 M18 exhibits only marginal distinctions from the authentic M18, subtle enough that only dedicated collectors might take notice. Notably, the civilian variant features different corrosion-resistant coatings on the internals and lacks certain markings specified in the M18 military contract, such as CAGE codes and part numbers. Additionally, while the M18 sports controls finished in flat dark earth, the P320 M18 opts for black controls.

In terms of the slide, there are nuanced distinctions between the M18 and the P320 M18. The military M18’s slide, apart from omitting the P320 M18 model designation, secures the rear sight plate with a single screw beneath the striker, as opposed to the P320 M18’s two screws flanking the striker. This design variance streamlines the removal and replacement of the rear sight plate on the civilian version, requiring less effort and disassembly, making it more user-friendly without the need for an armorer or gunsmith. Additionally, the rear sights on the P320 M18 boast green tritium vial inserts, diverging from the M18’s orange inserts, while both versions share green tritium vial front sights.

The ultimate distinction lies in the recoil spring and barrel fitting. The military M18 employs a slightly more robust recoil spring assembly to accommodate frequent use of +P+ duty loads and the military’s 115-grain truncated cone practice ammunition. Consequently, the barrel fitment on the M18 has been subtly altered to accommodate these higher-pressure military loads.

Design and Ergonomics

The M18 exhibits a design prowess that seamlessly combines functionality and aesthetics. Its modular polymer grip, a hallmark of the P320 series, offers a customizable fit catering to diverse hand sizes. This feature, shared with the M17, showcases SIG SAUER’s commitment to user comfort and adaptability. Both handguns share an intuitive control layout, making them suitable for both seasoned marksmen and those new to the handgun scene.

Parts to a Sig Sauer P320 M18 and M17 – M17 shown


At the core of the M18’s performance is its exceptional accuracy. The 3.9-inch barrel proves to be an optimal choice, delivering consistent and precise shot placement. This mirrors the performance excellence of the M17, highlighting SIG SAUER’s commitment to crafting handguns with unwavering reliability and precision. The M18’s crisp trigger, featuring a short reset, not only enhances shooting speed but maintains a focus on accuracy, much like its predecessor.

Durability and Construction

The M18, designed to meet the stringent standards of military contracts, exemplifies robust construction. The stainless-steel slide, fortified with a wear-resistant Nitron finish, ensures durability under demanding conditions. Akin to the M17, the M18 is engineered to withstand the test of time, establishing itself as a reliable companion for law enforcement professionals and civilian users alike.

Safety Features:

Both the M18 and the M17 prioritize user safety with a comprehensive array of features. From the striker safety to the three-point take-down safety system, each component is meticulously designed to prevent accidents and ensure secure firearm handling. The shared commitment to safety underscores SIG SAUER’s dedication to providing firearms that instill confidence in users.


A hallmark feature of the P320 series, modularity shines in both the M18 and the M17. The ability to interchange frames, slides, and barrels between these models offers users unparalleled versatility. This adaptability not only caters to diverse shooting preferences but also underscores SIG SAUER’s commitment to empowering users with customizable options.

Observations and Comparisons:

While the M18 and M17 share several commendable features, the M18’s compact size positions it as an ideal choice for concealed carry or those seeking a more maneuverable sidearm. On the other hand, the M17, with its larger frame, may appeal to those who prioritize a full-sized duty pistol.

About The Author

Tom Crandall

Tom has been writing about photography, cycling, running and fitness since 1988, covering everything from the product reviews to the latest in fitness trends. Tom is the Editor-in-chief of,,,, and a few other publications, he began racing in college while getting an Information Resource Management degree at George Mason University. Based in the photography and cycling-crazed city of Austin, Texas, with his wife Kathleen and pug Olaf, Tom enjoys running, walking or riding most every day.

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