I've had my MPX now for four years and I'm fed up with the intense trigger slap. I love the gun otherwise but my finger should not be aching after firing 100 rounds. I've read that it may be originating from the trigger mechanism. I've been waiting for Geisselle to offer their model but that was a year ago. I don't want to spend a few hundred on a Timney if Ill have the same problem. Any advice?

Maybe post this in the Rifle forum?

Thanks

The MPX will take any AR trigger. Doesnt have to be Geisselle. I put a Franklin binary trigger in mine. No issues.

Gonna have to disagree with Walker77 here - While the MPX may 'take' any AR trigger (not sure that's even accurate), that doesn't mean it's a good idea.

Geissele wont even warranty their MCX Trigger in the MPX, let alone an AR15 Trigger! Here's a quote from Geissele on the subject:

"The MPX has a very fast action, which is why the MPX ships with the Trigger Bridge, to protect the fire control group from the action. The MPX was designed to be used with the Trigger Bridge, our triggers were designed to be used with AR15 rifles using mil-spec components. While the MPX combination will work for a while, it will eventually fail. We want to be clear with our customers on this, and also have them know that we are working on an MPX specific trigger. We do not recommend using our AR15 triggers in these variants as it will void our warranty."

Bill Geissele knows triggers, probably better than anyone else in the industry. If he thinks there will be issues, you can probably take that to the bank. In all likelihood, those who haven't had any issues with an AR15 Trigger in an MPX, just haven't had any issues yet!

I tried a Geisselle and after about 1000 rounds , started getting trigger follow every few magazines.
I removed that trigger and put the KE Arms SL-1 trigger in its place. The SL-1 is approved for MPX use and it is a much better pull than the stock MPX.

Got the Timney Two-stage trigger for mine and tried it out this weekend. Works great, much better feel than the stock, and it’s specifically made for the MPX so it includes a bridge at the rear to keep the disconnector from being beat up. My finger felt fine.

Unfortunately, according to a post at arf.com, Geissele had dropped the idea of making a MPX specific trigger, which is strange since they make a MCX trigger that includes a bridge, even though Sig never felt the need to put a bridge on the MCX. Also posts that Larue recommends not using their trigger in the MPX, although they don’t seem to have stopped warranting it like Geissele did with their triggers.

Other tigger I was looking at was the Elftmann AR-9 trigger, which they claim has been extensively tested in the MPX. Probably would have been fine too, but decided to try the Timney.

I'd almost bet what Geissele did with the "MCX" trigger was once they figured out they could not make a reliable MPX trigger with the bridge, instead of scrapping the whole effort, they are making lemonade by turning it into the MCX trigger.

If you wonder how hard the MPX is on triggers, the Sig MPX small parts kit includes a spare hammer and bridge.

If I had to replace my MPX trigger (which honestly isn't that bad for what it is). I'd probably go with the Wilson TRU 9mm trigger. The trigger design in general is already well proven, and Wilson isn't going anywhere. The Timney is still beta testing and though they are not going anywhere either but some of their triggers have a reputation for being picky about being dirty etc. The SL-1 seems to be holding up okay. Lots of guys are running the Hiperfire triggers but there have been breakage reports too.

It seems like some MPX's are very hard on triggers and others are not. This might be tolerances, chosen ammo etc. There have been a LOT of conflicting reports with what does/doesn't work in the MPX with regard to ammo, gen1/2 magazine reliability, triggers, etc. and usually that points to tolerances in the guns themselves varying too much.

I would like to thank everyone for their time and advice in aiding me on making a choice on trigger replacement. I love everything about the gun with the exception of the damn trigger.

I have 1200 rounds through my MPX. While the trigger is not as nice as a mcx vertis, i have yet to experience any trigger slap. I put 130 rounds through it today, without issue.

I'm guessing trigger slap is something of a personal thing. I've been running an MPX in matches for awhile (like 10k rounds) and the trigger doesn't bother me in the least. Getting something aftermarket is problematic at least for me once Geissle decided to not do it. I'm not going to do a binary one, or an offbrand one.