SIG Sauer P320

The P320 chambered in 9×19mm Parabellum was introduced in the North American market on 15 January 2014, followed by the .45 ACP compact model at the SHOT Show in January 2015. On 19 January 2017, it was announced that a customized version of the SIG Sauer P320 had won the United States Army's XM17 Modular Handgun System competition. The full-sized model is known as the M17, and the compact carry-sized model is known as the M18. On 9 July 2025, United States Immigration and Customs Enforcement issued a memorandum stating all models of the SIG Sauer P320 were no longer approved, and officers must replace them with Glock 19 MOS pistols. On July 28, 2025, United States Immigration and Customs Enforcement extended its existing contract for the P320 duty pistol another two years, through July 2027. In December 2025, the SIG Sauer P320 replaced the SIG P220 as the Swiss Army's new service pistol. According to The Washington Post, the P320 is one of the most popular handguns in the United States. ==Design==

The P320 is a further development of the SIG Sauer P250, utilizing a striker-fired mechanism in lieu of a double action only hammer system. SIG lists the trigger pull of the standard P320 at . The P320 trigger pull is accomplished by a combination of a tensioned striker spring, ideal trigger shoe and trigger bar dimensions, sear/striker engagement, and a balanced trigger system. Ammunition The P320 can be chambered in 9×19mm Parabellum, .357 SIG, .40 S&W, .45 ACP, and 10mm Auto and can be easily converted from one caliber to another; a change from .357 SIG to .40 S&W requires only a barrel change; a change from 9mm to .357 SIG or .40 S&W (or vice versa) is accomplished using a caliber exchange kit. Because of differences in sizes, caliber exchange kits are only available between 9mm, .357 SIG, and .40 S&W. .45 ACP and 10mm require larger components and are not interchangeable with smaller calibers. Operation The P320 was designed to be ambidextrous in handling, sporting a catch lever on both sides of the slide and a user-reversible magazine release, and all other operating controls are designed to be operated from either side. The firearm can be field-stripped with no tools. Additionally, the firearm can be field stripped without depressing the trigger, an additional safety feature to prevent negligent discharge of the weapon. The fire control unit is removable, allowing the switch to a different grip size. Trigger system The P320 trigger shoe is available with a solid, all-metal trigger. Both curved and straight trigger shoe variants are available from SIG and from third-party aftermarket suppliers. ==Variants==

X Series models The X Series lineup includes the following grip module sizes: • Cd .357 SIG. The full-size slide also fits the carry-size grip module without any part of the recoil spring showing. • Full size – Fits any SIG P320 full-size slide in 9mm, .40 S&W, and .357 SIG In January 2019, SIG Sauer announced the XCompact handgun as the newest entry in their X Series lineup. • Compact size – As of March 2020, the P320 XCompact is available in 9mm only. The XCompact size grip module is the smallest grip module SIG currently carries, as they have not released a subcompact X Series grip module to date. In May 2022, SIG Sauer announced a 10mm Auto P320 variant, named the P320 XTEN. M17 The new US Army handgun requirements included a preference for an existing handgun model in the Modular Handgun System Request for Proposal, known as the XM17 Procurement. SIG Sauer submitted a P320 with a number of modifications and submitted it for the XM17 Modular Handgun System competition. Features include: • barrel length in carry size pistol • barrel length in full size pistol • Ambidextrous thumb safety • Chambered in 9×19mm Parabellum (can be adapted to fire larger calibers like .357 SIG, .40 S&W, and .45 ACP) • Improved slide sub-assembly to capture small components when disassembled • Improved trigger "mud flap" to prevent foreign debris from entering the pistol action • Loaded chamber indicator • Pistols chambered in 9 mm can feature a 17-round magazine as standard, with optional 21-round extended magazines available. • Slide cut-out to facilitate the addition of a reflex sight. (This is the slide from the RX Series) On 19 January 2017, it was announced that the SIG Sauer P320 MHS variant had won the United States Military's Modular Handgun System trials. The P320 will be known as the M17 (full size) and M18 (compact) in U.S. Military service. Though the pistol will remain chambered in 9 × 19 mm Parabellum rather than a larger caliber, the contract allows the services to procure SIG Sauer's proposed XM1152 Full Metal Jacket and XM1153 Special Purpose ammunition. 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 (XM18 compact version only), and 35,000 for the Marines. On 17 November 2017, soldiers of the 101st Airborne received the first XM17 and XM18 pistols, with over 2,000 handguns delivered. The XM17 has better accuracy and ergonomics, and tighter dispersion than the M9. It will also be fielded more widely, being issued down to squad and fireteam leaders; while special forces would dual-arm all of its members with a pistol and rifle; previously, junior leaders in regular infantry units were excluded from carrying sidearms but policy was changed to give them more choices and options in close quarters battle situations. All Army units are planned to replace the M9 with the M17 within a decade. X-Carry The X-Carry is a larger model of the XCompact featuring 17 rounds per magazine, compared to the Compact's 15 rounds, an enlarged grip, a longer slide, and a smaller slide lock. The X-Carry is the frame used for the M18. XFive Legion Released in late July/early August 2019, the XFIVE Legion is considered the flagship of the P320 platform that brings added weight and features. The TXG grip module has tungsten-infused directly into the polymer along with an attachable magazine well. It comes standard with Henning group aluminum base pads and a skeletonized flat trigger. The complete 9mm slide has lightening cuts in the top to reduce weight and assist in recoil. It is also optics ready through the removal of the rear sight plate assembly. The optics cut is the Delta Point/Romeo 1 Pro profile, but will accommodate multiple optics via adapter plates. P320-XTEN The SIG P320-XTENMAX is a 10mm Auto chambered X Series variant of the P320, released in 2022. It features an X Series grip module, bull barrel, flat X Series trigger and a Nitron-finished stainless steel slide with a cut for mounting aiming optics. Magazine capacity is 15 rounds. It weighs , has a bull barrel, overall length of , overall height of , overall width of and a sight radius of . P320MAX The SIG P320MAX is a sporterised variant of the P320, designed in 2021 for use by competition shooters. The pistol comes with ROMEO3 MAX sights and tungsten infused TXG heavy grip module, weighs , has a match grade barrel, and an overall length of . ==Problems==

Drop firing Initial production models of the P320 were found to have a "drop safety" issue if the firearm was dropped at a specific angle and height outside of SAAMI and NATO standards, potentially causing it to discharge. SIG Sauer has since refitted the P320 to further improve its drop safety and offers a voluntary upgrade program for early P320s. In late July 2017, the Dallas Police Department in Texas instructed all personnel to stop carrying the P320 pending an investigation. There were concerns that the firearm may discharge when it is dropped and the back of the slide hits the ground at a 33-degree angle. The problem was thought to be related to the trigger weight; some triggers were heavy enough that they essentially continued to move due to inertia after the gun hit the ground. Internet publications, such as TheTruthAboutGuns.com, conducted independent tests that appeared to confirm potential drop firings (at a 40 percent rate). On 8 August 2017, SIG Sauer issued a notice that they would upgrade all P320s to address the issue. The upgrade is described on the company's website as: "an alternate design that reduces the physical weight of the trigger, sear, and striker while additionally adding a mechanical disconnector." Issues of drop firing or shooting its user in the leg while holstered have continued sporadically with at least six departments removing the P320 from service. In June 2021, a technical investigation found that the misfire was due to "a partial depression of the trigger by a foreign object combined with simultaneous movement of the slide [...] that then allowed a round to be fired whilst the pistol was still holstered" and that the usage of a holster designed for a different pistol was a contributory factor; the P320 itself was not at fault nor were there any issues with how it had been procured by Canadian defence officials (since questions had been raised as to whether these officials were aware of the drop safety issues). However, the pistols would remain in storage pending a third-party safety assessment. The safety assessment and other proceedings related to the misfire were concluded by June 2022, with a decision to reinstate the P320 being taken towards the end of that month. Uncommanded discharge An investigation by The Washington Post and The Trace, published in April 2023, found more than 100 people who say their P320 discharged with no trigger pressure; at least 80 of them were wounded as a result, including 33 officers at 18 law enforcement agencies. At least 35 of the shootings are purported to have occurred with either post-2017 P320s with the updated design intended to address the drop firing problem, or older ones which had been updated by SIG Sauer. Reports of discharges have been recorded as early as 2016. Like some striker-fired pistols, the P320 is "effectively fully cocked at rest", since its striker is under constant spring pressure, which is released when the trigger is pulled. According to gunsmith James Tertin, this is a rare and "uniquely dangerous" configuration. The Fraternal Order of Police's Wisconsin state lodge recommended in mid-September 2022 that the state's police departments stop using the weapon, citing three Milwaukee Police officer injuries involving their service weapons or their partner's service weapons firing without any trigger pressure since 2020. In July 2025, Air Force Global Strike Command (AFGSC) ordered an indefinite "pause" on the use of the M18 pistol following a fatal incident at F.E. Warren Air Force Base involving a Security Forces Airman. The decision came shortly after the public disclosure of an FBI report highlighting concerns about uncommanded discharges in the P320-series. AFGSC stated the pause would remain pending investigations by the Air Force Office of Special Investigations and the command's safety office, with security forces being equipped with M4 rifles in the interim. The command also ordered 100% inspections of all its M18 handguns to identify any immediate safety concerns. An airman was arrested the next month under suspicion of having committed the offenses of making a false official statement, obstruction of justice, and involuntary manslaughter in connection with the death. In August 2025, the AFGSC reinstated the P320 for duty use, with 191 of 8,000 issued pistols requiring some repair or parts replacement due to suspected abnormal surface wear of internal parts. On July 9, 2025, the U.S. Department of Homeland Security issued an official memorandum directing U.S. Immigration and Customs Enforcement to discontinue use/carry of all models of the P320, and to instead purchase/supply the Glock 19 as a Replacement Duty Handgun. On July 28, 2025, ICE renewed its contract for SIG P320 service weapons through 2027. On July 31, 2025, the IDPA announced it was prohibiting the P320 from its competitions, explaining that "numerous reports and videos" alleging uncommanded discharges had made the matter "too visible to deny", while noting it possessed "no direct knowledge of any technical defect" with the firearm. Firearms media described the decision as the first blanket prohibition of the P320 by a national practical-shooting body and noted that other SIG Sauer handguns remain eligible within their respective IDPA divisions. IDPA stated that it would revisit the restriction in the future should new, credible information about the pistol's safety become available. Multiple organizations and firing ranges, such as the National Law Enforcement Firearms Instructors Association, have also banned the use of the P320 over unresolved safety concerns. and labeled those who made claims against the P320 as "uninformed and agenda-driven parties" despite evidence suggesting that the P320 has safety issues. ==Lawsuits==

Lawsuits involving the P320 include the following (listed chronologically). This list is not exhaustive. Steyr Arms, Inc. v. Sig Sauer, Inc. In May 2017, Steyr Arms, Inc. filed a patent infringement lawsuit against SIG Sauer via the United States District Court for the Northern District of Alabama. Steyr refers to their patent US6260301 (filed in 1999 and approved in 2001), which is for a handgun with a removable chassis. Steyr Arms requested a preliminary and permanent injunction to stop SIG Sauer from manufacturing and selling its P250 and P320 pistols. On 25 February 2020, the United States District Court for the District of New Hampshire granted SIG Sauer summary judgment, finding that SIG Sauer did not infringe Steyr's patents and dismissed all motions. Sheperis v. Sig Sauer, Inc. On August 4, 2017, four days before the Voluntary Upgrade Program was announced, Stamford Police Department SRT officer Vincent Sheperis filed a negligence action in the United States District Court for the District of Connecticut against SIG Sauer after his holstered P320 allegedly fell from the back of his vehicle and discharged a round into his knee on January 4, 2017. Although SIG reassured the public that the P320 design met industry standards regarding its drop safety, Sheperis's attorney, Jeff Bagnell, stated that the upgrade was telling. "The suit has been validated already", he said, adding that having SIG recall and fix the alleged defect is one of the demands listed in the complaint. SIG settled the case in June 2018. Vadnais v. Sig Sauer, Inc. On May 4, 2018, Loudoun County deputy sheriff Marcie D. Vadnais, through her attorney, Jeffrey S. Bagnell, filed a negligence action against SIG Sauer in the United States District Court for the Eastern District of Virginia after her holstered P320 allegedly discharged and broke her femur in half in February 2018 as she was removing it from her belt. The case settled on May 29, 2019, the second day of a jury trial. Leo Nielsen Trading ApS and Glock Ges.m.b.H v. Danish Defence Acquisition and Logistics Organization On March 15, 2019, Glock disputed the adoption of the P320 X-Carry into Danish military service, claiming the P320 did not meet DALO specification No. 79, which stated "No parts of the pistol shall be possible to mount incorrectly or in the wrong places." The case was won by Leo Nielsen Trading ApS and Glock Ges.m.b.H as they proved the ejector could be assembled incorrectly, were paid 30,000 Danish krones, and the purchase was cancelled. Later the contract was put out with different requirements, which the P320 fulfilled. Ortiz v. Sig Sauer, Inc. In September 2019, an Arizona gun owner who purchased a P320 in September 2016 initiated a class action lawsuit. It claims that SIG Sauer "continued to sell the flawed gun to the public", In March 2020, Judge Joseph N. Laplante denied SIG Sauer's motion to dismiss the case. The motion for class certification was denied in 2022. Green-Berrios v. Sig Sauer Inc. On January 4, 2022, a police officer, Elvis Ramon Green-Berrios, filed a lawsuit with the United States District Court for the District of Puerto Rico claiming that his service pistol, a P320, discharged without the trigger being pulled. Specifically, "As soon as he took hold of the holster at his waistband inside his pants, the P320 fired and hit him in his right thigh...". The lawsuit was dismissed in March 2025 after the plaintiff "admitting in court filed documents that his P320 pistol has no defects and does not discharge without a trigger pull." In a press release, SIG Sauer asserted this was the "18th frivolous or unsupported P320 unintentional discharge lawsuit dismissed". Armendariz, et al. v. Sig Sauer, Inc. On November 30, 2022, a lawsuit was filed in U.S. federal court alleging several P320 pistols unintentionally fired "without the trigger being pulled or deliberately actuated by the user". The lawsuit claims there have been "over 100 incidents" of such discharges, "many of which have caused severe injury". An attorney representing the lawsuit's plaintiffs, Robert Zimmerman, said it was the largest lawsuit against SIG Sauer involving the P320 on behalf of people who were injured. The 20 plaintiffs in the case (20 individuals and about a dozen spouses) are from 13 different states. Anderson, et al. v. Sig Sauer, Inc. On March 26, 2025, a group of 22 plaintiffs from 16 states filed a negligence and product liability lawsuit against SIG Sauer, asserting "uncommanded firing" of P320 pistols. The lead attorney for the plaintiffs claimed, "Sig knowingly designed and manufactured America's most dangerously-defective firearm". The lawsuit was filed with the United States District Court for the District of New Hampshire. Sig Sauer, Inc. v. Washington State Criminal Justice Training Commission On June 11, 2025, Sig Sauer filed a lawsuit against the Washington State Criminal Justice Training Commission (WSCJTC), Washington State's police academy, and their executive director, Monica Alexander, following its ban of the P320 from use on their firing ranges. The WSCJTC had banned the P320 following a report from an instructor in 2024 that a trainee's P320 had fired on a range without a trigger pull and established a task force investigating the weapon's safety prior to the ban. ==Users==