Same exact SIG trigger bars, same “675” part number, different results. One trigger bar reacted with “disconnector-like behavior” in both FCUs, and the other trigger bar did not, also in both FCUs. And there’s no way to know what is different about the trigger bars as they measure out in all dimensions to be equal. So, one is “bad” and it’s hard to say exactly why. Unless someone gets inside your FCU while the gun is fully assembled, and forces the sear forward with a hard metal poker, the trigger still must be cycled to get the gun to fire.
I have a 320 (plain jane model...not any tricked out ones) that I sent back during the "voluntary, totally not a recall" Sig offered when the issue first cropped up. Haven't had a problem yet. Also haven't dropped it either and it's always only gone bang when I've pulled the trigger. Still it gives me pause and the reason why I don't carry it and rely on it's little cousin, the P365. As far as I know that model has had no issues with drop safety.