Just got back from a local steel shoot which my SIG 320 X5. I have owned the gun a few years with a lot of rounds down range. The FCU was tuned by The SIG Armorer after purchasing the gun and he did a great job.

One time today, and the only time it has happened, the gun fired two rounds with one pull of the trigger. No idea how this happened, so I thought I would ask people smarter than myself.

You might want to contact Sig Armorer about that.

Just a WAG, has the hook at the tail end of the firing pin gotten worn down or bent? Or maybe the sear ledge has worn down? Maybe the sear return springs (under the sear) have weakened? I can't think of how else that might happen.

Good luck.

Thanks, if it happens again I will be contacting the SIG Armorer.