Originally Posted by
call_me_ski
Have we discussed a potential problem with reassembly?
I stole this from Reddit: user u/flatbreadcrisis
Possible Cause for P320 Accidental Discharges: Reassembly Error State
The Sig P320 can be assembled with the trigger group in an 'error state', in which the sear can drop unexpectedly and the trigger reset mechanism may malfunction.
\*\* Edit: link to pic of slide lock interacting in this way where the issue lies: There an extension on the trigger that has to push up but is blocked by a bar the disassembly lever moves into place. When the disassembly lever is rotated back, in order for that bar to move back forward out of the way the slide lock lever has to move upwards so a notch can slip back into place in a hole in the slide lock.
Second Pic showing sear engagement when it shouldnt:
Let's assume the slide is off of your P320 Pistol. The correct reassembly is as follows:
1. Put the slide on the rails
2. Pull the slide all the way to the rear
3. **Engage The Slide Hold to Lock the Slide Rearward By Pressing It Upwards (This is the critical step)**
4. Flip the disassembly lever and release the slide.
This is the correct reassembled state for the gun. However it is possible to get problems by simply doing this instead:
*3. Hold the slide to the rear manually with your hands, and leave the slide release in the downwards position.(this is wrong)*
While holding the slide back, you flip the lever and the gun will reassemble fine, and the trigger will appear to work. It may be a dead trigger at first, but a quick rack of the slide recocks and it seems fine. **However**\*\*,\*\* **by failing to push the slide release upwards at any point, the trigger is now in an error state**. It will remain so until the slide release is pushed upwards. In this state, the gun can be set off even by a firm shake, most commonly if the user pulls the slide part of the way back, then releases it forward (Similar to how you may check the chamber for a live round, not wanting to eject it.)
The trigger feels a bit squishy and off, not the usual pressure and firm snap but still you can hear the striker drop when pulled, and to an unsuspecting user it seems normal.In this state, a user could then put a magazine in the gun, then rack the slide, chambering a round, all without engaging the slide lock upwards. They would then pull the slide part ways back to inspect that a live round was in the chamber, setting the sear even more precariously than a full rack seems to, then maybe holster the gun. A sharp bump or shake is sufficient to often drop the sear in this state and set off a round.
The solution is simple, pull the slide all the way back again, and push up on the slide lock. You will hear a firm click as the trigger resets to a correct state. But it's pretty scary that you could end up in this state without ever having done anything apparently wrong. Most other guns you may be used to like Glocks don't require this critical step for their trigger upon reassembling.