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Key Points: The Sig Sauer M18, adopted as the U.S. military’s modular handgun in 2017, is a compact version of the M17 designed for adaptability, reliability, and longevity.

Based on the Sig P320 chassis, it features a modular fire control unit (FCU) that allows customization of grips and slides.

-The M18 uses 9mm ammunition, including Winchester’s M1152 FMJ and M1153 Special Purpose rounds, which offer improved accuracy and reduced collateral damage.

-With a 17+1 round capacity, polymer frame, and Picatinny rails for attachments, the M18 is set to serve the U.S. military for decades while also being available to civilians as the Sig P320/M18.

Sig Sauer M18: The U.S. Military’s Modular Handgun for the Future

The folks at Sig Sauer make some great weapons, and I have had the pleasure of owning a few myself.

The military did everyone a great service when they ditched the Beretta M9 pistols, which I hated when I was in the military. But that is for another time. 

In 2017, the US Army held a contest to decide which pistol would be chosen for the XM17 Modular Handgun contest.

Contestants included Sig Sauer, CZ, Beretta, Smith and Wesson, FN Herstal, Glock, Kriss USA, and STI. The contest was for two weapons.

The Sig Sauer M17 was chosen as the new Army service modular handgun.

The M17 is the full-size version, and the M18 is the smaller “compact” version. 

Sig Sauer M17. Image: Creative Commons.

Sig Sauer And Glock… Naturally

The Sig entrant narrowly beat out the Glock 19, which was…and is a great pistol.

Many Special Operations units use the Glock, and I got to fire one at an indoor shoothouse with some Special Forces guys a few years ago. After a quick familiarization, we put several hundred rounds down range, and it was an excellent pistol.

Glock released the 19 in the civilian market and sold 100,000 Glock 19s in just six months. But what was the deciding factor besides the fact that Sig Sauer was $100,000 cheaper? The ammunition.

Sig and Winchester are a Winner

Sig Sauer wisely partnered with Winchester Arms for the competition, which already supplies much of the Army’s ammunition. Sig Sauer combined their bid with two specific kinds of ammo, Winchester’s M1152 Full Metal Jacket and M1153 Special Purpose loads. 

The M1152’s 115-grain FMJ-FP round leaves out of the 5-inch pistol barrel of the SIG Sauer M17 at 1,320 feet per second and delivers 445 foot-pounds of energy at the muzzle. It is a flat-nosed round that the company claims will improve accuracy.

Sig Sauer P320 Compact

Sig Sauer P320: Image Credit: Creative Commons.

The Special Purpose load utilizes a 147-grain jacketed hollow point (JHP) projectile. The intended use of the M1153 ammo is in situations where overpenetration is a concern to minimize collateral damage.

M18: Key Details and Facts 

The M18 is based on the Sig Sauer P320; civilians can buy the civilian version, the Sig Sauer P320/M18, directly from the manufacturer. 

Sig Sauer M18 Specs

Caliber 9x19mm

Barrel Length 3.9″

Overall Length 7.2″

Slide Length 6.5″

Width Overall 1.6″

Height W/O Mag 5.5″

Weight Unloaded 28.1 oz / 1.75 lbs

Avg Trigger Pull 4.5 lbs

Standard Capacity 17+1

Sights White Dot/Night

Finish Coyote PVD

So What Does Modularity Mean?

The Sig Sauer M18 and its big brother, the M17, are polymer-framed, striker-fired 9mm pistols based on the Sig P320 handgun chassis system. That means that the fire control unit is the serialized part.

The FCU (fire control unit) can be swapped for different grip modules and accommodate different slide sizes to better fit the user’s hands.

However, the only grip modules on the service versions of the Sig Sauer M18 are the ones shipped from the factory. That won’t be the case in Special Operations units, where SOCOM will buy different grips depending on the shooters and the missions involved.

Sig Sauer makes 10, 12, 17, and 30-round magazines for the M18.

The Army knows that modularity means longevity. If you have a weapon system that can constantly changed and upgraded, depending on the mission or new requirements, then it is much easier (and cheaper) to keep that weapon on the books.

The M18 can easily change grips and slides for customization. The Picatinny rails allow for a variety of lights or other enhancements. I was never a red dot guy until I fired the Glock with the SF guys. I learned my lesson.

The M18 shoots wonderfully well, and it will make our military training easy to accomplish. 

The Sig Sauer M18 is another outstanding weapon produced by the good folks in New Hampshire.

As a military service handgun, it should last for decades. 

About the Author: 

Steve Balestrieri is a 19FortyFive National Security Columnist. He served as a US Army Special Forces NCO and Warrant Officer. In addition to writing for 1945, he covers the NFL for PatsFans.com and is a member of the Pro Football Writers of America (PFWA). His work was regularly featured in other military publications.