10 Reported Problems with the Sig M18: Common Issues and User Experiences

The Sig Sauer M18 has become a common sidearm for military and law enforcement. Many users appreciate its modular design and reliable performance. Still, several problems with the M18 have been reported by different groups, leading to new discussions about its safety and use.

Understanding the issues that have been observed with the Sig Sauer M18 helps owners and potential buyers make informed decisions. With the M18 in wide service, reviewing these reported concerns gives a clearer picture of what people are experiencing with the pistol.

1) Unintentional discharge while holstered reported by Michigan State Police in 2024

In July 2024, an officer with the Michigan State Police experienced an unexpected discharge from a Sig M18 pistol while the gun was still in its holster. The event happened in front of multiple witnesses, leading to an official investigation.

According to a 32-page FBI report, testing showed it was possible for the M18 to fire without the trigger being pulled. The report found that actions like repeated holstering or movement while in the holster could disable a key safety feature inside the gun.

The FBI's Ballistic Research Facility confirmed these findings, noting the gun had discharged because the internal safety could be rendered inoperable by normal movements an officer might make. This raised concerns about the reliability of the safety mechanisms in the M18.

The incident sparked renewed public attention because the gun was not dropped or mishandled at the time. Instead, the problem occurred while the pistol was worn on duty, highlighting the risk in everyday police work. More information can be found at Outdoor Life's article on the incident.

2) FBI confirmed M18 fired without trigger pull during evaluation

During an evaluation, the FBI found that the Sig Sauer M18 could fire without anyone pulling the trigger. This happened when certain safety features failed during testing. The issue was called an "uncommanded discharge."

This problem raised concerns about the reliability and safety of the M18. The FBI report did not find every M18 at risk, but it showed the possibility exists if the safeties do not work as designed.

The findings added to ongoing discussions about reported problems with the M18 and its related P320 models. Many agencies had already pointed out similar problems in recent years.

Some people worry about carrying or using the pistol because of this risk. Safety experts are urging users to be extra careful until the issue is fully understood and fixed. For more information, visit this FBI report explains SIG Sauer M18 safety concerns.

3) Modified triggers by MSP caused safety concerns

The Michigan State Police (MSP) made changes to the triggers on their Sig M18 pistols. These modifications were done after they noticed issues with some triggers not working, which they called "dead" triggers.

To fix the problem, Sig Sauer found that the triggers were out of specification. They decided to grind off a tiny amount of metal—about 0.020 inches—on each trigger. Most of the modified triggers were installed by Sig Sauer, but some were put in by MSP armorers trained on the M18 platform.

Concerns were later raised about whether these trigger adjustments created new safety risks. The changes were related to reports of pistols firing without the trigger being pulled, leading to investigations and technical reviews.

A federal ballistics report examined one of these incidents and found it was possible for the M18 to fire without a trigger pull under certain conditions. This added to ongoing worries about the safety of the modified triggers for law enforcement officers using the weapon. For more information, see the detailed report on trigger modifications and safety concerns.

4) Air Force Global Strike Command paused M18 use after fatal incident

In July 2025, Air Force Global Strike Command temporarily stopped using the M18 pistol after a fatal shooting involving an airman at F.E. Warren Air Force Base in Wyoming. The pause began on July 21, following the incident that happened the previous day.

The command ordered all units to stop using the M18 Modular Handgun System for both operations and training. This decision will remain until further notice, as officials continue their investigation into what happened.

Concerns about the M18 pistol’s safety were renewed by this event. The M18, a military version of the Sig Sauer P320, had already faced reports of unintentional discharges. The recent death led leaders to take extra measures to review its use.

More details about the pause are available from the announcement by Air Force Global Strike Command. The incident and the pause have been covered by several news outlets, including Defense News and Stripes. For more information, see the full report from Air Force Global Strike Command and coverage by Defense News.

5) Trigger safety lock can become ineffective with normal law enforcement movements

Some users have reported that the trigger safety lock on the Sig M18 may not always work as intended when the gun is handled in stressful or fast-paced environments, such as law enforcement situations. The safety lever is designed to block the trigger unless direct pressure is applied to it.

If the trigger area is bumped or brushed during normal movements, the safety lever might not block the trigger as effectively as expected. This can increase the risk of an unintentional trigger press.

Concerns about the reliability of the trigger safety have led to debate within the firearms community and among police agencies. Claims have surfaced that the trigger safety's effectiveness can decrease when the gun is holstered, unholstered, or moved rapidly.

Some lawsuits and accident reports allege that the issue has resulted in accidental discharges. These claims continue to raise questions about the trigger safety system's ability to prevent unintended firing during routine police use.

SIG Sauer has responded to these concerns by defending the design and citing results from safety tests. However, the discussion around the trigger safety remains active, especially among law enforcement professionals.

6) Grounding triggers by 0.020 inches done to fix 'dead trigger' issues

Some SIG M18 pistols had problems where the trigger would not reset after firing. This is sometimes called a "dead trigger" problem. When this happens, pulling the trigger does nothing, even with a loaded magazine and a slide that is forward.

To address this, some departments reported that triggers were modified or "ground down" by about 0.020 inches. This small change was made to help the trigger reset properly and prevent the dead trigger issue from returning.

This solution came after officers experienced repeated malfunctions during use, which led to concerns about reliability. Modifying the trigger was seen as a quick fix by some armorers. The FBI mentioned this adjustment in connection with earlier dead trigger problems found in M18 models.

While grinding down the trigger addressed the reset in some cases, it was not an official fix from SIG Sauer. Anyone considering changes to trigger assemblies should be cautious. Making modifications can affect warranty and long-term safety.

7) Fatal uncommanded discharge at F.E. Warren Air Force Base in Wyoming

In July 2025, a Security Forces airman was killed at F.E. Warren Air Force Base in Wyoming. The incident happened when a holstered SIG M18 handgun discharged without anyone pulling the trigger.

The bullet struck the airman in the chest, and he did not survive his injuries. This raised major concerns about the safety of the M18.

Following the fatal shooting, the Air Force Global Strike Command immediately paused use of all M18 pistols. This decision was made to protect other service members while the cause of the uncommanded discharge is investigated.

Reports say this pause will last until safety reviews are complete and the Air Force is certain the pistol is safe to use. The tragedy brought new attention to previous claims about unintentional discharges involving SIG P320-series pistols.

The incident at F.E. Warren shows how a single event can change military policy and bring up questions about weapon reliability. Authorities continue to look into what caused the weapon to fire while holstered.

8) Legal scrutiny surrounding P320 platform inclusive of M18

The Sig Sauer M18 is part of the P320 platform, which has faced legal challenges in recent years. Lawsuits have been filed against Sig Sauer by civilians, law enforcement, and others who allege unintentional discharges from these pistols.

Concerns about unintentional firing have led to multiple lawsuits and investigations. Some complaints claim the pistols can fire without the trigger being pulled under certain conditions.

Major media outlets and law enforcement agencies have highlighted the issue of accidental discharges, raising questions about the safety of the P320 and M18 models. Lawsuits allege injuries and damages connected to these incidents.

Law enforcement agencies in the United States have reviewed their use of the Sig M18 after recent reports and incidents. Some departments have even temporarily stopped using the pistol while further safety evaluations continue.

Government agencies, including the military, have also shown concern. After a fatal incident at an Air Force base, the military paused their use of the M18 as part of their review process. Learn more about these legal and operational actions involving the M18 and P320 platform.

9) Reports of M18 firing without command led to military investigations

Concerns over the Sig Sauer M18 increased after reports suggested that the pistol could sometimes fire without the trigger being pulled. This issue was flagged by both military and law enforcement personnel. Some users experienced unintended discharges under normal handling conditions.

After a tragic incident at F.E. Warren Air Force Base, the Air Force paused use of the M18 across its units. The incident raised new questions about the reliability of the pistol’s safety systems. Investigations were launched to find the cause and determine if the weapon was safe to use.

The FBI also evaluated the M18’s safety features. They found that under certain circumstances, the internal safety mechanisms might fail, causing unintentional firing. Similar problems have been noted with the civilian P320, which shares the same design as the military M18.

Multiple news outlets covered these developments as the military responded to reports of unintended discharges. These reports led to broad reviews and paused deployment of the weapon pending further results.

10) FBI 32-page report detailing M18 safety issues released publicly

In July 2025, the FBI made public a 32-page report about the SIG Sauer M18 pistol. This document investigated claims that the M18 can fire without anyone pulling the trigger. These concerns have been linked to both police and military incidents.

The FBI tested the pistol’s striker-fired system and noted it uses several safety mechanisms. Despite these features, the report documented cases where the M18 fired during normal handling, not from intentional trigger pulls. This raised questions about whether physical movements alone could cause an unintentional discharge.

The FBI’s findings suggested that regular activities by law enforcement officers could lead to what they called “uncommanded discharges.” The agency released the report after pressure grew from multiple high-profile events involving the M18.

This evaluation added to ongoing debates about the handgun’s reliability and safety. The full FBI report can be found detailed online, including confirmation of an uncommanded discharge. Law enforcement and military agencies are now reviewing their use of the SIG M18 because of these findings.

Understanding the SIG M18’s Design and Features

The SIG M18 stands out as the compact version of the U.S. military’s Modular Handgun System. Its setup, materials, and functions set it apart from many other handguns used by armed forces and civilians.

Key Distinctions from Other SIG Models

The SIG M18 is based on the SIG P320 platform but was adapted for specific military needs. Unlike some older SIG models, such as the P226 or P229, the M18 features a striker-fired system instead of a hammer-fired mechanism. This change results in a consistent trigger pull and simpler internal design.

The M18 comes with a manual thumb safety, which is not standard on all SIG P320 versions. Its modular fire control unit allows the user to switch grip frames, slides, and barrels with ease. This modularity helps the M18 fit different hand sizes and mission requirements.

Magazine capacity is also notable. The M18 can accept both compact and full-size 9mm magazines, adding flexibility for different settings. Its ambidextrous controls accommodate left- and right-handed shooters.

Materials and Build Quality

The M18’s slide is made from stainless steel with a corrosion-resistant coating, designed to handle harsh environments. The frame uses a polymer material, making the pistol lighter without losing durability.

Small parts like the barrel are made with quality steel to withstand high use in military conditions. The handgun’s parts are built to tight tolerances, aiming for reliable performance and long service life. Seals around the slide and barrel help keep out dirt and moisture.

Its finish helps prevent rust even with regular exposure to sweat, rain, or sand. The overall build quality of the M18 focuses on longevity, reliability, and user comfort during long periods of handling or operation.

Maintenance and Troubleshooting Recommendations

Proper care and timely troubleshooting help prevent many issues with the Sig M18. Staying informed about cleaning steps and official support options makes ownership easier and helps maintain pistol safety.

Routine Care for Reliability

Routine cleaning after shooting is important for the M18. The user should field strip the pistol, making sure to clean the barrel, slide, and frame rails. Build-up in these areas can lead to malfunctions like failure to eject or feed. Regular inspection for excessive wear, dirt, or broken parts is needed.

Proper lubrication is also necessary. Lightly apply oil to the moving parts, including the slide rails and barrel. Over-oiling should be avoided as it attracts dirt. List of key steps:

• Unload and disassemble

• Clean barrel and slide

• Check and replace worn parts

• Lightly lubricate assembly points

Using factory recommended cleaning supplies further reduces the chance of reliability problems.

Manufacturer Support Resources

The Sig Sauer M18 ships with a detailed owner’s manual. This manual explains safe handling, regular care, and instructions for replacing certain parts. Users should read the manual and keep it for reference.

For problems beyond basic cleaning, the company offers customer support by phone, website, and email. Owners can request help on warranty claims, repairs, and parts replacement. SIG’s website has guides, FAQs, and recall updates. The military maintenance manual for the M18 is available online and provides more advanced repair steps. For deeper technical support or persistent concerns, using these manufacturer resources is recommended.

Frequently Asked Questions

Recent reports mention issues with the SIG M18’s drop safety and trigger safety, as well as reliability questions in some settings. The military and police have experienced unintentional discharges and some departments have temporarily stopped using the handgun.

What are the known issues with the SIG M18's trigger safety?

The SIG M18 has faced problems with its trigger safety system. In one case, the FBI confirmed that a Michigan State Police officer’s M18 discharged while holstered, even when the trigger was not touched. The internal striker safety lock can become ineffective under typical movements by law enforcement, which raises concerns about accidental discharges. More about this can be found in this breakdown of SIG Sauer M18 safety concerns.

Has there been a recall on the Sig Sauer M18 and what did it address?

As of now, there has not been a full recall of the SIG M18. While SIG Sauer did issue a voluntary upgrade for the P320 series years ago related to drop safety, the M18’s unique issues have not led to a dedicated recall. Police agencies and the military have, however, reviewed the weapon’s use and temporarily halted usage at times following incidents.

Are there reports of accuracy problems with the Sig M18 compared to the M17?

Accuracy between the M18 and M17 is generally consistent, as they share similar internal designs. However, some users have reported issues with the sights on the M18 becoming misaligned, which can affect accuracy. Adjusting or replacing the sights can help, but there is no widespread concern about the M18 being less accurate by design. Details about these problems with M18 sights are discussed in this summary of Sig Sauer M18 issues and fixes.

What are the differences in handling malfunctions between the Sig M17 and M18 models?

Functionally, the M17 and M18 handle malfunctions in similar ways, since both are based on the same modular platform. Reports suggest that neither model has unique or more frequent malfunction types compared to the other with regular use. Maintenance routines and parts are also largely interchangeable.

How has the SIG M18 performed in military service in terms of reliability?

The SIG M18 has seen widespread use across several branches of the U.S. military. While it has performed well in many areas, there have been incidents—such as the Air Force pausing M18 usage—after fatal accidents involving the pistol. Some reliability concerns stem from issues with accidental discharges, but major reliability failures unrelated to safety are not often reported. Comprehensive evaluation is ongoing in some military commands after reported incidents, as described in this report on recent Sig Sauer M18 issues.

What steps has SIG taken to address the accidental discharge concerns in the M18?

SIG Sauer has acknowledged concerns with accidental discharges, especially those involving the P320 platform’s safety systems. Engineering reviews and voluntary upgrades have been implemented in the past, but no specific recall or hardware change has been introduced for the M18 in response to the recent incidents. Departments have also updated training and reviewed protocols due to these safety concerns.