LaRue MBT-2S Trigger in a Sig MCX...? Need help...

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[ARCHIVED THREAD] - LaRue MBT-2S Trigger in a Sig MCX...? Need help...

Posted: 2/14/2017 6:32:11 PM EDT

So I recently got my MCX in 5.56 and took it to the range.

Ran 150 rounds of AE .223 no issues. Trigger was heavy but no terrible.

Most of my guns have Geissele triggers so I figured I'd try a LaRue MBT in this gun since Geissele has gone back and forth on supporting the MCX.

Got my LaRue trigger and threw a set of fixed sights on my gun as I plan to run it with irons.

Took it to the range today and it wouldn't fire... no primer strike.. anyone have experience with this...? Hammer profile is different but I'm not seeing the issue jump out at me.

Posted: 2/14/2017 6:39:52 PM EDT

[#1]

Any pictures?

Posted: 2/14/2017 6:51:05 PM EDT

[#2]

Sorry no... I just put the OEM trigger/ hammer back in.

I thought I'd read where guys were using LaRue triggers in their MPX/MCX

I put a Geissele SSA-E in my MPX with zero issues.

Posted: 2/14/2017 7:11:01 PM EDT

[#3]

Weird. What kind of ammo? Something with unusually hard primers? Do you have an AR you could try the MBT in just to see if it works in that platform? I'd trouble-shoot it that way.

Posted: 2/14/2017 7:19:10 PM EDT

[#4]

Good idea...

It was Federal (American Eagle) 55gr .223 never had an issue with thousands of rounds.

Posted: 2/14/2017 7:54:13 PM EDT

[#5]

If yours is the upgraded Mcx, the LaRue will not work with the firing pin lock. Take out your bolt carrier group. If there is a pivoting bar that comes down at the head of the firing pin, the LaRue hammer will not push it out of the way and allow the firing pin to move and hit the primer. The older versions of the Mcx bolt carrier group would work with the LaRue and I had a LaRue in mine until the recall/upgrade. You must have a new Mcx. Is your serial number 25,000 or higher?

Posted: 2/14/2017 8:29:04 PM EDT

[#6]

Quote History

Quoted:
If yours is the upgraded Mcx, the LaRue will not work with the firing pin lock. Take out your bolt carrier group. If there is a pivoting bar that comes down at the head of the firing pin, the LaRue hammer will not push it out of the way and allow the firing pin to move and hit the primer. The older versions of the Mcx bolt carrier group would work with the LaRue and I had a LaRue in mine until the recall/upgrade. You must have a new Mcx. Is your serial number 25,000 or higher?

View Quote

Makes sense.

Posted: 2/14/2017 11:45:07 PM EDT

[#7]

Yes sir.... it's a new MCX with the upgraded BCG

Well... I guess I'll have to wait until Geissele releases their MCX trigger

Now I have a LaRue MBT with nothing to put it in..... (ponders new rifle build)

Posted: 2/18/2017 2:08:42 PM EDT

[#8]

Can you remove the firing pin block?

Posted: 2/19/2017 11:51:56 PM EDT

[#9]

So is there the same issue with the Geissele trigger? I too had the recall and just swapped out my carrier assembly....have a trigger I was going to place but if no go...

Posted: 2/20/2017 8:06:54 AM EDT

[#10]

Quote History

Quoted:
So is there the same issue with the Geissele trigger? I too had the recall and just swapped out my carrier assembly....have a trigger I was going to place but if no go...

View Quote

The MCX will break the Geissele and G won't cover it under warranty. I'm not sure if the G trigger will activate the safety or not.

[ARCHIVED THREAD] - LaRue MBT-2S Trigger in a Sig MCX...? Need help...

Armory » Sig Rifles

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