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MCX and MPX Trigger Upgrade

32781 Views 35 Replies 21 Participants Last post by Indianaeph, Dec 24, 2016

COBE

Discussion Starter · May 10, 2016

Would appreciate your advice and experience! I have an MPX SBR in Form 4 prison, just purchased an MCX 300/5.56 carbine this weekend, and submitting Form 1 for MCX 300 SBR. I believe there is significant agreement that the Sig trigger assembly needs serious improvement. I saw a Sig sponsored video indicating a non-Sig trigger replacement does not void Sig warranty (just trigger warranty). Need help upgrading the Sig triggers! Suggestions?

1 - 20 of 36 Posts

kansascity45

· #2 · May 10, 2016

Congrats on your new MCX!! Think I saw your pic on another thread, very cool 300 & 556 kit. Hope to see your range reports soon too.

Yeah, my original MCX carbine's trigger wasn't really bad, just too stiff. It's such a nice rifle, seemed she deserved a nice trigger too. We have Geissele triggers in couple of ARs here SSA & a 3 gun, but there are other great options...

Cheers

branson1369

· #3 · May 10, 2016

Running Geiselle SD3G with zero issues other than the MPX is an ammo eater...LOL

Reactions: 1

Soncar22

· #4 · May 10, 2016

I am running a Geissele SSA-E in my MCX and MPX and they both are working wonders. Due to the high impulse of the MPX, most triggers that are too similar to the milspec AR-15 trigger have issues with trigger slap or don't work. The SSA-E Hammer is designed differently and doesn't have that longer C in the back and therefore doesn't make contact with the lower trigger assembly. Before the SSA-E, i installed a BCM trigger and got trigger slapped all day.

aplus1234

· #5 · May 10, 2016

Wilson Combat single stage TTU in my MPX

COBE

Discussion Starter · #6 · May 10, 2016

Wow, thanks for the quick responses and your experiences. How did you handle the stock trigger bridge? I keep thinking Sig spent additional time/money to develop it, does it need to stay installed? Will upgrade triggers easily fit the bridge?

aplus1234

· #7 · May 10, 2016

COBE said:
Wow, thanks for the quick responses and your experiences. How did you handle the stock trigger bridge? I keep thinking Sig spent additional time/money to develop it, does it need to stay installed? Will upgrade triggers easily fit the bridge?

This video will answer your questions. It's a great video

https://m.youtube.com/watch?v=AVzu-ja6FI0

Reactions: 1

cdavis

· #8 · May 10, 2016

I decided to try the Larue MBT which is a very nice and a welcome change from the stock MCX trigger; as would any premium trigger I imagine.

Soncar22

· #9 · May 10, 2016

The Geissele Triggers don't need the bridge and will not fit it. Due to the design of the SSA-E, the Hammer will not travel back far enough to make contact with the trigger. Even if it does fail, Geissele will honor their lifetime warranty.

COBE

Discussion Starter · #10 · May 10, 2016

Thanks for all the options in triggers (you can probably tell I am a newbe in this area). I researched the Geissele triggers and between your experience and the online reviews, looks like a solid upgrade.

I decided to contact them for any additional insights. They responded: “Geissele triggers should withstand the hard impact of the MPX/MCX blowback. Please keep in mind our triggers are designed for the AR-15 MIL-SPEC 5.56 platform and unfortunately we have not tested them in the Gen 1 or 2 MPX or MCX. Customers have had success with our AR-15 triggers in the MCX Gen 1 without the stock trigger bridge. We would recommend an SSA or SSA-E over a 3 Gun trigger due to the longer sear engagement and the better chance of it resetting. The S3G has a very short pull and reset. With some direct blowback AR15 rifles, the modified bolts (ramped bolt) causes reset issues, the bolt does not push the hammer down far enough to catch the disconnect.”

So, plan to order the SSA-E for the MCX. Like the idea of the 3G short pull and reset, might try on my MPX when I receive it. Thanks to all again, very helpful!

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Reactions: 2

Soncar22

· #11 · May 11, 2016

Just to clarify the MCX does not have a trigger bridge. Only the MPX comes with one on the stock trigger.

Reactions: 2

IUOE Mike

· #12 · May 11, 2016

My MPX has a Geissele SD-E trigger installed. No issues to date, Geissele said they will warranty the trigger when used in a MPX. Good enough for me.

gundrted

· #13 · May 12, 2016

I just installed a Timney 2-Stage Red Straight trigger into my MCX. I haven't taken it to the range yet, WOW is it crisp. Install was a breeze and I've never changed a trigger on an AR (this is my first AR). The scariest part was driving out the pin for the safety.

AR-15 Competition Replacement Trigger

kansascity45

· #14 · May 12, 2016

gundrted said:
I just installed a Timney 2-Stage Red Straight trigger into my MCX. I haven't taken it to the range yet, WOW is it crisp. Install was a breeze and I've never changed a trigger on an AR (this is my first AR). The scariest part was driving out the pin for the safety.

AR-15 Competition Replacement Trigger

Looks like a very nice trigger there. I shoot with a guy running Timney in his Colt AR, and it's one of the best shooting AR's I've seen..

Yeah, that selector switch is a pain to remove. It's easier to remove the grip. You can then simply turn the selector rearward, and out of the way to remove & re-install the trigger...

Cheers

gundrted

· #15 · May 12, 2016

kansascity45 said:
Yeah, that selector switch is a pain to remove. It's easier to remove the grip. You can then simply turn the selector rearward, and out of the way to remove & re-install the trigger...

That would have been very helpful last week.

Reactions: 1

mej16489

· #16 · May 12, 2016

Its not necessary to remove the selector nor the grip (to allow the selector more rotation) to remove the MPX trigger and bridge. It just take lots of fiddling with the selector position while rotating up the bridge follow by the trigger/disconnector.

Its much easier to get an SSA/SSA-E in then it is to get the original out.

I had loaned out some tools on the day that my SSA came in and it wasn't possible for me to remove the grip for the easy-peasy method.

branson1369

· #17 · May 12, 2016

gundrted said:
That would have been very helpful last week.

Did not have to do either with min just a little patience and a couple jiggles

DHC

· #18 · May 13, 2016 (Edited)

Geissele SSA. Massive upgrade, the thing shoots like butter now.

Reactions: 1

gundrted

· #19 · May 16, 2016

I went to the range over the weekend and WOW ... The Timney 2-Stage trigger is SOOOOOOO much better than the stock trigger. I was way more consistent with the new trigger too. The wall on the second stage is perfect. Just a little pressure at the wall and snap (or BANG). There is just enough first stage travel where you can take it up and shoot, hold or back off. I'll be getting a second one for my SBR lower build.

$225 isn't cheap, but it may be the best money I've spent on a gun upgrade. I had to readjust my Mepro M21 because I found I was pulling the gun less and didn't need to compensate for it any more.

Hands down. Amazing.

Reactions: 2

COBE

Discussion Starter · #20 · May 17, 2016

Yea Haw! My wife tells me my Geissele SSA-E package just arrived. Going to install and take it for a range test when I arrive home this weekend. Thanks again for everyone's guidance.

Reactions: 1

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