On January 19, 2017, the U.S. Army announced SIG Sauer’s P320 variant as the winner of the Modular Handgun System trials. The full-size and compact variants were adopted as the M17 and M18, respectively, by the Army. In 2019, the Marine Corps ordered the M18 and began equipping Marines across the fleet with the new pistol. On February 14, 2023, an incident occurred aboard Camp Foster, Okinawa, involving a Marine-issued M18.
New Hampshire Public Radio acquired the investigation report, released April 4, 2023, via a Freedom of Information Act request. The report notes that Person 1 (P1) was issued an M18 with two 17-round magazines; one magazine was inserted into the pistol, a round was chambered, the safety was engaged, and the M18 was holstered with the cover rotated over it. These actions were witnessed by Person 3 (P3). Along with Person 2 (P2), P1 and P3 proceeded to Gate 1 for guard duty. For nearly five hours, P1 and P2 rotated standing at the ID checkpoint until 10:00AM when P1’s M18 discharged while standing at the checkpoint.
P2’s statement notes that P2 was in the guard shack and heard a loud noise. Upon exiting, P2 found P1 shaking and nervous. P2 asked what happened and P1 responded that the M18 discharged. After checking to see that P1 was ok, P2 visually checked with P1 that the M18 was on safe and called to report the incident. P1’s holster was damaged when the M18 discharged.
The Marine Corps report noted that P1 completed classroom training and hands-on training for the M18 at Camp Hansen, Okinawa, on November 8, 2021, with the most recent training on August 30, 2022. Furthermore, the maintenance record of the M18 showed that it passed inspection and was found to be serviceable on November 22, 2022. A subsequent inspection after the discharge incident also found the pistol to be serviceable. At the time of the incident, P1 had 7 years and 11 months as a Japanese Security Guard while P2 and P3 had 20 years and 13 years and 2 months of experience, respectively. The report also notes that P1 was not taking medication, did not drink alcohol, and was well-rested the night before the incident.
After reviewing security camera video footage, the Marine Corps investigator concluded that P1 did not mishandle the M18 prior to the discharge. From the evidence and statements of the people involved, the investigation concludes that the M18 was on safe and secured in the holster. As a result, the investigator recommended that an engineering review of the M18 be conducted. On March 7, 2025, SIG Sauer released a statement affirming, “The P320 CANNOT, under any circumstances, discharge without a trigger pull – that is a fact. The allegations against the P320 are nothing more than individuals seeking to profit or avoid personal responsibility.”
Additionally, the Marine Corps investigator recommended that the policy on weapon condition status be reviewed. Rather than having the M18 in condition 1 with a round chambered and the safety on, the investigator recommends that condition 3 with a magazine inserted but no round chambered be employed during lower Force Protection Condition levels. This reduced level of readiness would be in contrast to the Marine Corps policy utilized for the M9 and M45A1 pistols which called for them to have a round chambered and safety engaged when being carried by Marines and civilian law enforcement and security personnel.