A Friendly FFL’s Take on the FBI’s M18 Evaluation
I like all guns. Polymer or steel, striker or hammer—if it goes pew‑pew I’ll probably find something to appreciate. That said, a recent FBI Ballistic Research Facility report on the SIG Sauer P320/M18 caught my attention, because it pokes straight at a fear every carrier has had at least once: Could my pistol fire when I’m not even touching the trigger?
Quick disclaimer: I’m not a gunsmith, engineer, or metallurgist. I’m the guy behind the counter at an FFL who cleans a lot of guns, shoots a bunch of them, and reads too many technical documents after the shop closes. So take this for what it is—one shooter’s plain‑English read of a dense government report. If you think I’m off base, let’s talk about it.
What Happened?
Michigan State Police switched from Glock to the SIG M18 (a military‑trim P320). One of their motor officers was standing there minding his own business when—inside a Level 3 Alien Gear duty holster—his pistol fired a round. No one had a finger anywhere near the trigger.
The FBI’s Ballistic Research Facility got the gun, holster, and ammo and ran it through 30‑plus pages of X‑rays, high‑speed video, torture tests, and a generous helping of “let’s poke it with a punch and see what breaks.” You can read the full document here:
https://drive.google.com/file/d/1L7RXrneHlzfjrewMFIeeyc-nel3bsDnM/view
My Layman’s Summary of the Findings
- Two things must fail at once.
- The sear (the shelf that holds the striker back) has to let go.
- The striker safety lock—the final physical barrier that’s supposed to block the striker unless the trigger bar lifts it—has to be out of the way at that exact moment.
- Slide/frame pressure can nudge those parts enough to line up for an unlucky shot.
Holster squeeze, wrestling with a suspect, or even just leaning hard against a patrol car can flex a polymer frame. In the P320’s design that flex can move the captive safety lever and its spring, which in turn can leave the striker lock hanging uselessly above its channel. - The FBI reproduced live‑round discharges without touching the trigger.
Using a punch to knock the sear off its notch (to simulate wear or shock) and then simply pressing/twisting the holstered pistol, they got nine live primers to ignite and left dents on several more. - It’s unlikely but not impossible.
Thousands of cops carry P320s daily without incident, but “unlikely” isn’t the same as “can’t happen.”
How Does This Compare to Glock‑Style Designs?
Glock (and the Canik MC9 Prime I’ve been playing with lately) uses a vertical plunger in the slide. The trigger bar directly cams that plunger up and out of the striker’s path. When you let off the trigger, gravity and a stout spring ram it straight back down into its hole. Simple, hard to misalign, and less sensitive to frame flex.
SIG chose a modular fire‑control unit with a side‑pivoting safety lever and a tiny coil spring that isn’t pinned in place. Elegantly modular—but the spring can walk and the lever can bump under stress, leaving the striker block AWOL.
My Practical Takeaways
- Know your gear. If you carry a P320, keep the fire‑control unit clean and bone‑dry—oil collects grit that gums springs.
- Use a rigid holster that fully shields the trigger. The FBI also showed that a simple key could snake in and press the trigger through the side of some duty holsters. Don’t give Murphy that kind of invitation.
- Hammer guns still rock. Double‑action SIG P226, Beretta 92, 1911—old‑school guns put the firing pin dead still until the hammer actually falls. Fewer moving safeties, more visible status.
- Training matters more than brand loyalty. If your department mandates P320s, understand its quirks and check it during every cleaning session. If you’re shopping for yourself, weigh all the factors—ergonomics, track record, parts cost, and, yes, the safety architecture.
Final Word
I’m not ditching my own striker guns over this report, but I’m also not pretending it doesn’t exist. Every design has trade‑offs; the P320’s give us a slick modular chassis and excellent trigger feel, but at the cost of extra complexity in the safety path. Read the FBI paper, make up your own mind, and—as always—keep your booger hook off the bang switch.
Stay safe, keep it clean, and shoot straight.