I usually shoot my P320 wearing gloves for a couple of reasons, not least because prior to the factory modification I got a nasty jab from the trigger when firing the gun to the point of developing a bloody blister even during relatively short sessions. The original Apex Tactical Specialties flat trigger helped, but I still ground off part of the projection at the bottom.

After receiving the pistol back from the upgrade, I continued shooting it wearing gloves, but yesterday finally decided to try it without. Although the session without consisted of only 30 rounds, there was no more sensation of stinging or jabbing (or bloody blister). I don’t know if the change was due to something about how the modification affected the trigger mechanism, or just because of the trigger design change. I like the flat triggers that have suddenly become available for many models, but at this point I’m not sure I’ll replace the new factory version.

I'm late to the flat trigger business, but I think I could get used to it.

Of late, I've read a lot of people talking about "trigger sting," but what or where is it? I've had some slide and hammer bite in the past, but never a trigger problem such that there was blistering or pain.

How does it happen?

I keep hearing about it, but it wasn't present in my P320's before the upgrade, nor after.

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Of late, I've read a lot of people talking about "trigger sting," but what or where is it? I've had some slide and hammer bite in the past, but never a trigger problem such that there was blistering or pain.

The CZ P-01 I bought October of last year bites me big time. The trigger digs into the "bony" part of my finger and rubs a blister/hole after ~20 double-action pulls. There is also an additional "back-bite" when the gun recoils. It is unusable in this condition. I believe this is because of the sharp curvature at the bottom. Cajun Gun Works has different triggers with less curvature which they say stops this "trigger bite." But, unlike the OP, I shoot a P320, both before and after the safety upgrade in which the trigger was replaced, in complete comfort.

I believe the problem I had was due primarily to the shape of the trigger and how my finger curves to the bottom of the trigger guard. The bottom leading edge of original factory trigger poked into my finger and there seemed to be the “back bite” or “back jab” during recoil that egregore described. The Apex flat trigger helped, but even the small projection at the bottom was an issue. I suspect that the reason I’m not experiencing it now is because the shape of the new trigger that contacts my finger differently.

I can imagine that not every shooter would experience things the same way due to trigger finger differences.

Interesting. Supposed to get mine back today via Fedex.

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The original P320 trigger caused a stinging sensation or pain in some shooter's trigger fingers. Hickok 45 mentions this in his initial review of the P320.

The original trigger was hollowed out on the back side all the way to the tip. SIG redesigned the trigger and the new trigger became known as the "adverse trigger". This trigger was filled in on the tip of the backside and also had a forward projection off the trigger shoe which became known as the "mud flap" to protect the internals from debris entry at the bottom of the trigger well. This seemed to alleviate the trigger sting issue for most.

When I first saw the newly designed low mass trigger that is part of the SIG "voluntary upgrade" I noticed that it was hollowed out all the way to the tip and wondered if this would produce trigger sting. Both of my P320s came with the second generation "adverse" trigger and I never had any issues with them.

After my full-size P320 45 came back from the upgrade, I shot a couple of magazines on a fairly cold day and experienced some trigger finger sting. But I have shot it twice more in warmer conditions since then and had no trouble. I have also not had any issues with my compact P320 9 mm since the upgrade.

My presumption, and that of others, is that the hollow-back trigger allows high frequency vibrations to be transmitted down the trigger shoe against the finger in response to recoil. I have read accounts from a few others who have experienced some trigger sting with the new trigger.

I have not experienced it either before or after the upgrade. Could the hollowed out backside of the trigger be filled in with silicone or epoxy to reduce the effect. Not sure if that would negate the upgrade though.

My 357Sig compact definitely has a bit more sting to it than it had before the upgrade.
Not blister inducing, but noticeable.

Sent in a 45 Compact and it came back with the "sting". It was perfect before the upgrade. I put a Gen2 Apex flat trigger but the sting was still there.

Next range trip I was shooting reactive targets instead of paper. Was having more fun than just shooting paper, and I forgot to notice the sting. Not going to worry about it anymore.

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Originally posted by sigfreund:
I believe the problem I had was due primarily to the shape of the trigger and how my finger curves to the bottom of the trigger guard. The bottom leading edge of original factory trigger poked into my finger and there seemed to be the “back bite” or “back jab” during recoil that egregore described. The Apex flat trigger helped, but even the small projection at the bottom was an issue. I suspect that the reason I’m not experiencing it now is because the shape of the new trigger that contacts my finger differently.

I can imagine that not every shooter would experience things the same way due to trigger finger differences.

That was my opinion as well. I sanded the sharp edge of the trigger guard and that helped a lot. 800 rounds in one day, had no more blister.