[12] 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.

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.

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 Marine Corps.

[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 (FMJ) and XM1153 Special Purpose/Jacketed Hollow Point (JHP) ammunition.

The rear slide cocking serrations of the regular M17 are replaced with "XXI", a reference to the twenty-one steps the guards take on their patrol in front of the tomb, as well as the 21-gun salute.

The wood grips are crafted from wooden planks removed from the deck of the USS Olympia, the ship which carried the first Unknown Soldier to the United States in 1921.

The P320-M17 stainless steel slide is PVD coated and the control elements feature a black finish like found on later military M17 service pistol batches.

A commemorative edition was also released, called simply the M17 Commemorative, produced in the exact specification of the original gun delivered to the army, including brown trigger and controls, the same choice of magazines selected by the military, and delivered in a plain cardboard box rather than the normal SIG Sauer hard sided black plastic case, just as military pistols were packaged.

[29] In 2020, SIG released the P320-M18 model for civilians, which features the same adaptation of the military configuration, this time with the shorter carry size M18.