SIG Sauer M17

• Slide cut out to facilitate the addition of a reflex sight; this is the slide from the RX Series.[6]
• 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.
• 120 mm (4.7 in) barrel length in full-size M17.
• 98 mm (3.9 in) barrel length in carry-size M18.
• Chambered in 9mm NATO; unable to adopt other calibers or frames because of the spanner screw on the frame's chassis.
• A 17-round standard magazine, with an optional 21-round extended magazine available.[7]
• Steel components are given a physical vapor deposition (PVD) corrosion-resistant finish.[8]
• Using spanner screws instead of normal screws to resist disassembly further than field stripping by non-armorer users.[9]

The Modular Handgun System has self-illuminating tritium sights for low-light conditions, an integrated rail for attaching enablers and an Army standard suppressor conversion kit for attaching an acoustic/flash suppressor.[10] Every M17/M18 handgun is test fired before leaving the factory with 13 rounds -- three to break in the weapon and ten to test accuracy.[11]

On January 19, 2017, the United States Army announced that the SIG Sauer P320 MHS variant had won the military's Modular Handgun System trials. The modified P320 was subsequently designated the M17 (Full-Size) and M18 (Carry) for U.S. military service. The M17 has better accuracy and ergonomics and tighter dispersion than the Beretta M9 and will be fielded more widely, being issued down to squad and fireteam leaders. US special operations forces operators are all dual-armed with a pistol and a rifle. Junior leaders in regular infantry units who were previously excluded from carrying sidearms will be given more choices and options in close quarters battle situations under a new policy. All Army units are planned to have the M9 replaced with the M17 within a decade.[12][13]

In May 2017, the Army announced that the first unit that will receive the M17 would be the 101st Airborne Division by the end of the year. At the same time, the rest of the U.S. Armed Forces revealed they also intend to acquire the handgun, making it the standard sidearm for the entire U.S. military. The services plan to procure up to 421,000 weapons in total; 195,000 for the Army, 130,000 for the Air Force, 61,000 for the Navy (M18 compact version only), and 35,000 for the Marines.[14][15] The US Army primarily ordered the M17 version, whilst the Air Force and Navy opted for the M18 version as their standard service pistol.

In 2019, the Marine Corps selected the M18 to replace several pistols. While the other services had previously primarily fielded the Beretta M9 and M9A1, the Corps also planned to replace its M45A1 and M007 pistols with the M18.[16][17] The M45A1 was made by Colt and the only recently fielded M007 was made by Glock.[17] The Marines began rolling out the M18 in 2020.[18]

Although it was initially announced that the U.S. Coast Guard would adopt the M17/18 handgun, the agency announced in September 2020 that they would acquire Glock 19 Gen 5 handguns through a DHS procurement.[19] In November 2019, SIG Sauer announced the delivery of the 100,000th M17/M18 handgun to the U.S. military.[20]

Though the pistol remained chambered in 9mm NATO rather than a larger caliber, the contract allowed the Army and other services to procure SIG Sauer' s proposed XM1152 Full Metal Jacket and XM1153 Special Purpose ammunition.[21][22] The ammunition is a "Winchester jacketed hollow-point" round; similar in appearance to the Winchester PDX1 round but with some differences to the design of the hollow-point petals. One round is a standard 115 grain ball, designated the M1152, the other is a 147 grain Special Purpose round designated the M1153. Olin Corporation (Winchester Brand) received a contract to produce approximately 1.2 million rounds of the ammunition.[23]

The first annual report for the XM17/XM18 Modular Handgun System (MHS) program assessment recommended the Army:[24]

1. Upon identification of the root cause of the double ejections and ball ammunition reliability problems, confirm fixes to both the XM17 and XM18 in future testing.
2. Work with the vendor to identify and eliminate cause of variability in the manufacture of the trigger group mechanism.
3. Consider redesign of the slide catch lever and other operator training changes to prevent engagement by operators while shooting the pistol.

The pistols are serialized with a unique set of serial numbers that incorporate items of significance to the Old Guard: "LS" represents line six of the Sentinels' Creed, "My standard will remain perfection"; "02JUL37" to signify the first 24-hour guard posted at the Tomb of the Unknown on July 3, 1937; and "21" to signify the 21 steps it takes the Tomb Sentinels to walk by the Tomb of the Unknown and the military honor of a 21 Gun Salute.[26]

Tomb Sentinels carry loaded weapons, with the 21-round magazine inserted into the pistol. The magazines are customized, and feature an aluminum base plate engraved with the names of the Greek figures featured on the Tomb of the Unknown – Peace, Victory, and Valor – and include a name plate on the bottom of the magazine engraved with the Tomb Sentinel badge number.[26]