Sig Sauer P320 Root Cause Found?

In Friday’s LinkSwarm, we covered how Sig Sauer’s problem with uncommanded discharges from the P320 got still more serious with the death of an Air Force airman. This has been a low-level, intermittent story that’s been bubbling on for many years now, with no root cause anyone could find for the problem.

Well, we may finally have the root cause.

But first the caveat: I am not a gunsmith, and I have no way to determine how plausible the explanation is, if the methodology is sound, or if the applies to a significant number of P320s rather than the one the YouTuber is testing.

Executive Summary: YouTuber Wyoming Gun Project was able to get repeated P320 discharges by putting one millimeter of pressure (not a full pull) on the trigger and manipulating the overly loose slide.

That should not happen.

If you just want to skip to the money shot, skip to the beginning of the second video. But first up, I have Forgotten Weapons’ Ian McCollum describing the issue in detail with his usual clarity. (I don’t think he had seen Wyoming Gun Project’s video before recording this.)

  • “Things have changed again for Sig with the death of a US Air Force serviceman, from apparently a P320 in its holster. Obviously, not good.”
  • “I think it has gotten to the point where Sig is now faced with a problem they cannot solve. They have two problems now. One of them in theory they can solve, and that is a hypothetical mechanical problem with the 320 that causes it to fire without someone pulling the trigger or commanding it to fire.”
  • I’m skipping over the part where he says that no root cause was found, because, again, this video came presumably out before he had a chance to see the Wyoming Gun Project video.
  • “There have been dozens of [P320] lawsuits, and only two of them have actually come back with Sig being found liable.”
  • “But even if they do fix it, they have a secondary problem right now that I don’t think is surmountable. They can theoretically fix the mechanical problem. What they cannot fix is the reputational issue.”
  • “The fundamental issue here is that the 320 doesn’t offer anything different from any of its competitors.” Shooters originally liked the modular design, but now lots of platforms do that, and now there are better choices in the same space. No institutional buyer is going to choose the P320 over competing choices now because the risk is too high.
  • “What does the SIG 320 offer us that would convince us to buy it despite this element of unknown potential risk? Nothing. That’s the problem.”
  • “There are actually three separate problems with the 320. Two of them absolutely 100% provable. The third one is still the jury’s out, literally and figuratively.”
  • “Problem number one was the drop safety. There was a legit drop safety problem with the original 320s. And it’s entirely Sig’s fault. They should have been more careful. That’s like, you know, it’s not like surprise drop safety. What? We didn’t even think about drop safety. No, they they should have been more careful.”
  • “And when the guns proved to have a drop safety fault, they didn’t recall them, presumably because that would have been super expensive even at that point. They offered a voluntary upgrade, which a lot of people didn’t get because they’re like, ‘Ah, my gun doesn’t need it. It’s fine. It’s voluntary. That means it’s not that important.'”
  • “Because that happened, Sig got into people’s heads, oh, that’s the gun that fires if you drop it. And it was true. I mean, within the limitations of the actual mechanical flaws of the drop safety.”
  • “The second issue is Sig did not put a trigger safety on the 320. Do you technically need it? No.” Presumably to differentiate on better trigger feel.
  • McCollum thinks that’s a mistake. “It’s not an issue with the trigger pull and it very much does prevent accidental discharges with holsters. If your holster is kind of wonky, if you get your shirt caught when you’re holstering the pistol. Absolutely a thing that can happen and that does happen and that a trigger safety will often prevent from turning into a fired gun.”
  • “I don’t know how many of their unintended discharge incidents are the result of something catching on the trigger and unintentionally pulling it, but I feel pretty safe assuming it’s greater than 0%. And so if they had a trigger safety on the gun, it would have prevented some percentage of these issues.”
  • Given the first two problems, shooters now just assume there’s a third, still unidentified flaw lurking in the gun.
  • “If you’re another gun company looking at this situation, I think one of the lessons to take away from it is you need to take safety seriously enough that you address it in positions where, you know, do we really need to hand like is this enough of a safety issue that we really need to do it? Maybe make sure that you’ve pushed that decision boundary pretty darn close to yes, we should always do something in favor of more safety in the design.”
  • “Could Sig survive recalling all the 320s that are out there? I don’t know. Maybe, maybe not.”
  • “Looking at the other guns that Sig has available, I think their best option would be to expand the P365 in scope and scale this thing out of production and replace it. You know, they’ve got the 365 macro, come up with like the 365 service issue size. The P365 is a fundamentally different mechanism than the 320.”
  • “The 320 is a development off the P250. And that’s probably where some of its problems originate from, if not all of them.”
  • Now the Wyoming Gun Project video:

    It’s a 40 minute video, because he goes into significant detail on his methodology. So you get lots of caliper measurement, among other things.

  • “Basically we were able to input a millimeter or less of downward movement on the sear and get this slide by manipulating the slide. We’re able to get it to go off and actually fire a primed case five times in a row.”

    That’s bad.

  • Measuring off the grip: “66.62mm was where the wall was. So that’s the start. That’s the end of the pre-travel, but the start of the actual trigger pull where we’re moving parts, right?”
  • 65.69 is where he’s able to set the screw so that the striker will actuate by touching the slide.
  • “I’m not a math wiz, but that’s less than one millimeter. Less than one millimeter into the firing sequence and it just dropped the striker.”
  • “If this trigger, this trigger assembly in here is less than 1mm out of spec, you could have a potential problem.”
  • “That’s kind of simulating of it’s rolling around in a cop’s holster. Now, we saw the first one was less than a millimeter. So, if one of these parts is out of spec, less than a millimeter, or what if this is able to because this affects the trigger when you pull it back.”
  • The screw, which a lot of people have focused on, is to simulate the 1mm pull without having the inherent imprecision having an actual human finger there would introduce. “This is a tool to simulate to take the human factor out so that you same people that will come in my comments and say this aren’t going, ‘You pulled the trigger with your finger, bro.’ I didn’t. I didn’t. But I simulated a human taking up the pre-travel going through the firing motion or the firing sequence.”
  • “The FBI report said there was a ledge on, it was either the sear or the the striker hook, I don’t remember, and you pulled the trigger a little bit less than a millimeter, less than one millimeter, and it caught on that ledge and then you holstered your gun. Okay, this is a G-code holster. Then you holstered your gun, and it just went off.”
  • “So some people were like, ‘Put it in a holster and see if it goes off.’ There it is.”
  • I’m skipping over a lot of methodology walk-through here.
  • “There should be absolutely no way that you should be able to put input into the slide and it drops the striker. No way. There should be none.”
  • “Why, if you move the slide, will it set the sear off? If you’re halfway into the if you’re not even halfway less than a millimeter, less than one millimeter, and you bump the slide, and it has the potential to go off.”
  • He gets the gun to fire with the 1mm screw setting by manipulating the slide, and seems very surprised that he could do it.
  • “The striker safety is working. Look at that. The spring is working. Holy crap. Holy crap.”
  • Then he gets the P320 to go off again, under the same circumstances, four more times. “That was five in a row, guys. Five in a row. Is that consistent enough for some of the people out there? Do you want me to do it every day until Sig fixes the gun?”
  • While this is not quite “vice-gripped to a test mount on a granite slab table in an FBI safety lab” level quality control, it does indeed seem pretty repeatable. It’s a cascading failure where two separate things have to go wrong. But neither of those two separate things is some inconceivable, unlikely scenario.

    Bonus video: Penguinz0 commenting on the situation, which is where I first heard about the Wyoming Gun Project video, and includes a lot of footage from that video, if you just want the Cliff Notes version.

  • “It’s a widely reported problem apparently linked to more than a hundred incidents since 2016, with at least 80 injuries.” Ouch! If those numbers are true, it seems this is a much wider-spread problem than I thought.
  • “Even in my neck of the woods here in Tampa, an officer in 2020 had the weapon fire while in his jacket while he was adjusting it.”
  • “I don’t think this is going to happen all the time to every P320 out there, but the fact that it can happen at all is concerning.”
  • All of this renewed interest in P320 discharges probably wouldn’t happen if Sig hadn’t gone out of their way to declare that there was no way P320s could discharge on their own. That probably goes down with the Twitter employee who banned the Babylon Bee as one of the greatest social media backfires of all time.

    For a looking at a completely different series of cascading failures, see my analysis of the Pipe Alpha disaster.

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    21 Responses to “Sig Sauer P320 Root Cause Found?”

    1. 10x25mm says:

      The inserted screw is connecting the trigger to the slide stop in the loose, high mileage P.320 used in this video. This .45 ACP P.320 has much more play between the FCU, the slide, and the frame than my much lower mileage 9x19mm P.320.

      My P.320 will not slide wiggle discharge with either an inserted screw or the two screw external fixator frame I devised to create 1mm (0.040 inch) of trigger pretravel.

      I bought my full sized, no safety P.320 specifically to explore the reported uncommanded discharges. It is an updated pistol which was the oldest NOS gun I could find locally. Think it was manufactured in 2019. So far, I have been unable to effect an uncommanded discharge.

    2. Malthus says:

      From Gunsite Academy: “Currently, there are significant questions being asked in our community about the operation of the SIG 320 Pistol.

      “After much consideration, we have decided that until these questions have been answered to our satisfaction, Gunsite will no longer allow the SIG 320 Pistol to be used in classes, effective immediately.

      “If the SIG 320 is a government-issued duty pistol for Military or Law Enforcement students, we will allow – but discourage the use of – the SIG P320 for that student”

      To the best of my knowledge, this is the only gun ban ever announced by Gunsite. If the P320’s reliability has been so badly compromised that it is unsafe for range use, SIG will be forced to recall and redesign the pistol.

      They need to move fast if they hope to salvage their reputation.

    3. Lawrence Person says:

      KR Training also instituted a slightly less restrictive policy for P320s, and I bet a lot of other training academies/range owners are doing so.

    4. Shifty Bitwise says:

      This reminds me when they put outriggers on the Suzuki Samurai ( which I owned at the time ) and PURPOSELY made it tip over.

      “See it tips over ! “

    5. 10x25mm says:

      Something is very wrong with the P.320 used in the Wyoming Gun Project video. The striker safety lock in his very high mileage .45 ACP P.320 is not functioning.

      That striker safety lock prevents the striker from releasing until the trigger is moved at least 2 mm to the rear. The video author claims he was able to strike primers with only a 1 mm rearward trigger movement. A good illustration of the P320 striker safety lock operation can be viewed in this “The Truth About Guns” post:

      ‘Why Did the The Washington Post and The Trace Misrepresent the SIG P320’s Safety System in Their Hit Piece?’ authored by Jeremy S. on April 24, 2023.

      Also, the inserted screw’s connection of the trigger to the slide stop in his P.320 is why the pistol discharged when it was inserted into the holster. The pistol’s slide stop actuated the trigger.

      SIG Sauer is being set up by the gun control mob.

    6. Malthus says:

      “SIG Sauer is being set up by the gun control mob.”

      …because Gunsite Academy is in the vanguard of firearms prohibition activity.

    7. 10x25mm says:

      “…because Gunsite Academy is in the vanguard of firearms prohibition activity.”

      Because Gunsite Academy, like SIG’s detractors in the legal sphere, have no competency in mechanical engineering, so they go with the flow. Gunsite has had no uncommanded P.320 discharges and had no basis for their action, except accommodating Zimmerman and the other gun control lawyers who are attempting to destroy SIG.

    8. Greg Green says:

      “This reminds me when they put outriggers on the Suzuki Samurai…”

      “Because Gunsite Academy, like SIG’s detractors in the legal sphere…”

      Where are there other guns that release the striker or firing pin when the slide is wiggled? How is this acceptable to you?

    9. Greg Green says:

      Someone claimed this test was like someone setting a brick on the gas pedal of a car and then being surprised when the car races off.

      That’s incorrect. This is like setting a brick so lightly on the gas pedal that the car doesn’t move, then wiggling the steering wheel and the car races off, while the brick is still only lightly on the gas pedal.

    10. 10x25mm says:

      “Where are there other guns that release the striker or firing pin when the slide is wiggled? How is this acceptable to you?”

      We know without any doubt that something is very wrong with the P.320 used in the Wyoming Gun Project video. The striker safety lock in his very high mileage .45 ACP P.320 is not functioning. It prevents the striker from going full travel until the trigger is pulled 2mm. In this case, the video author claims that the subject P.320’s trigger was pulled only 1mm. The striker safety lock should have blocked full travel of the striker, but clearly did not.

      Whether the striker safety lock failure to function was due to deliberate modification, misassembly, or some kind of profound wear/breakage has not been established. It can be said, however, that this pistol was not functioning as designed; that a major feature of the design had been disabled.

      This kind of uncommanded discharge is common in Colt SAA revolvers and U.S. Model 1911 pistols which have broken parts, or have been subjected to hack trigger jobs. No one criticizes the venerable designs of the SAA or 1911 when wear/breakage/misassembly/deliberate damage produces uncommanded discharges.

    11. 10x25mm says:

      “Someone claimed this test was like someone setting a brick on the gas pedal of a car and then being surprised when the car races off.

      That’s incorrect. This is like setting a brick so lightly on the gas pedal that the car doesn’t move, then wiggling the steering wheel and the car races off, while the brick is still only lightly on the gas pedal.”

      The more appropriate analogy would be someone cutting all the brake lines on the car and then wondering why the car crashed the first time the driver needed to stop.

    12. 10x25mm says:

      SIG Sauer just issued a statement on the P.320 today which as been posted in its entirety on Shooting News Weekly:

      ‘SIG SAUER Issues a Statement on the Safety of P320 Platform Pistols’
      By Dan Zimmerman • July 30, 2025

      The money shot, for Malthus:

      “P320 Range and Training Bans

      Following several of these inaccurate reports, a number of ranges, training providers, and training facilities made the reactionary decision to ban the P320 and its use in their facilities. We are actively working to provide these individuals with accurate information along with a detailed understanding of the P320 and its safety features. If you are impacted by a P320 range or a training provider ban, we urge you to reach out to SIG CUSTOMER SERVICE: 603-610-3000 Option 1 or send a message here so we can clarify any misinformation and provide the truth.

      The P320 CANNOT, under any circumstances, discharge without the trigger first being moved to the rear. This has been verified through exhaustive testing by SIG SAUER engineers, the U.S. Military, several major federal and state law enforcement agencies, and independent laboratories. This video provides a detailed view into all of the various safety features of the P320 and provides a detailed explanation of how the safety system works; for further information on the P320 please visit here…..”

      SIG Sauer is suffering unrelenting, unjustified attacks by Robert W. Zimmerman, a partner at Saltz Mongeluzzi Bendesky “Trial Lawyers”.

    13. Malthus says:

      “Because Gunsite Academy, like SIG’s detractors in the legal sphere, have no competency in mechanical engineering.”

      You don’t know that. Gunsite has offered customized 1911s for many years, not a one of which has shot their owners.

      “The P320 CANNOT, under any circumstances, discharge without the trigger first being moved to the rear.”

      Then quite clearly the dead airmen was not shot dead by his P320, which is far more bewildering that if he had.

    14. 10x25mm says:

      “You don’t know that. Gunsite has offered customized 1911s for many years, not a one of which has shot their owners.”

      Yes I do. They have no mechanical engineers or engineering laboratory. They rely on contract gunsmiths for some work on premises, but they are not engineers. I don’t believe any of them have even attended the SIG Sauer P.320 armorer’s class.

      “Then quite clearly the dead airmen was not shot dead by his P320, which is far more bewildering that if he had.”

      It will be quite some time before we know the full circumstances of the F.E. Warren Air Force Base incident.

      It took a year to tease out the facts in the Michigan State Police incident and they still have not been made public. The MSP incident was due to prior damage to the pistol and a complete bungle by the FBI BRF excited clowns like you for months.

    15. Malthus says:

      “It will be quite some time before we know the full circumstances of the F.E. Warren Air Force Base incident..”

      But until such time as a detailed forensic investigation is completed, we have full assurance from SIG’s mechanical engineers that their problematic pistol is safe to use and the response by ICE, the Air Force and Gunsite Academy is foolish and unwarranted.

      Comrade Cartridge has weighed the evidence from afar and declares the P320 to be reliable and dependable. Any government agency or training academy that disputes his verdict is to be be discredited and ignored.

    16. 10x25mm says:

      “But until such time as a detailed forensic investigation is completed, we have full assurance from SIG’s mechanical engineers that their problematic pistol is safe to use and the response by ICE, the Air Force and Gunsite Academy is foolish and unwarranted.”

      Guilt assignment before proof is your modus operandii? That is what the DEI clowns at FBI BRF and MSP did, and now they have had to walk back their bogus analysis. They spent a year creating a false narrative for chuckleheads like you. The SIG engineers that you snidely denigrate, on the other hand, never wavered. They actually did a real engineering analysis.

      The simple fact is no one has been able to make an engineering case against the P.320 trigger mechanism, beyond the very peculiar drop discharges which were resolved in 2016. Zimmerman’s “experts” have been a gunsmith and a risk analyst who were unable to explain how the claimed uncommanded discharges happened, but still were allowed to disparage the pistol design in court. Team Zimmerman have had 10 years to conduct “a detailed forensic investigation” of any claimed uncommanded discharge and have chosen not done so.

      The only weapons technology which would continue in use under your modus operandii would be rocks. There is an element of risk in any technology more sophisticated which you are unwilling to accept. You simply don’t deserve to use firearms.

      Read the Gunsite Academy Fakebook post on the P.320 and tell us how they made an engineering case against the P.320. The post doesn’t. It is just more hive mentality.

    17. James Bobby says:

      So it’s a dangerous, cheaply made piece of juck. Got it.

    18. Malthus says:

      “Guilt assignment before proof is your modus operandii?”

      We have a dead airman in immediate proximity to his issue pistol. Occam’s razor says he was shot by that gun. Absent human agency, the pistol would seem to be lethal to its owner.

    19. 10x25mm says:

      “We have a dead airman in immediate proximity to his issue pistol. Occam’s razor says he was shot by that gun. Absent human agency, the pistol would seem to be lethal to its owner.”

      There are 27,000 accidental shootings in the United States annually. About half are self inflicted. 500 to 1,000 are fatal.

      Do we ban every firearm model involved in each of the 13,500 self inflicted accidents? Or just the 250 to 500 firearm models involved in fatal, self inflicted shootings? Before any investigation?

    20. […] Sig Sauer’s constant denials, the crisis over uncommanded P320 discharges continues to mount, and the Houston Police Department just pulled the weapon as a duty […]

    21. […] our previous examination of Sig Sauer’s P320 uncommanded discharges issue, a whole lot of commenters seem to get hung up on the screw, ignoring the methodology that Wyoming […]

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