Larue Triggers NOT for PCCs (at least the MBT-2S)

[Cameramonkey]

Found my answer @Beowulf .

First, Larue customer service is awesome. I got an email response over a weekend, in about 24 hours. So that is awesome.


I tried upgrading my AR PCC with a Larue MBT-2S trigger for a moderate, affordable upgrade.
I finally got out to the range yesterday and the rifle acted bizarrely. It was a single shot AR. It would fire and cycle completely, but the trigger wouldnt latch and the hammer would ride the bolt closed.

If I hand cycled the bolt, it would eject the unfired round, and latch the hammer. I assumed it was just dirty so I took it home to clean it. When I got the trigger out I remembered that I had upgraded over the winter, so I emailed tech support Last night (Saturday).

At 9:45PM tonight (Sunday) They responded:

We do not recommend using our triggers with a 9mm. This has been know to happen so I would discontinue use of the trigger with this rifle. It is only designed to work with ar15 and ar10 rifles, not pcc rifles.

Huh. Interesting. Maybe just not enough energy to get it to catch? They didnt elaborate.

Asking for an RMA. My only other non-PCC AR already has a MUCH better Timney trigger. Hopefully their awesome customer service extends into this. (and they update the product page with a warning?)

Just wanted to put this out there for anyone looking to upgrade their PCC trigger.

 

[snorko]

I had the same issue with a Kart trigger in an AR with a .22LR upper. Switched to a low cost PSA factory lower and it cleared up. Put the lower with the Kart trigger under a Bushmaster Varmint upper and it worked great.

 

[Cameramonkey]

Unfortunately, my only other dedicated 223 lower already has a Timney mid grade trigger. I'm sure since I have all the packaging and its still LNIB an RMA will be issued. At least I hope. (given their reputation, I assume they will make it right since its not documented)

 

[NyleRN]

PCC ARs have to have a full profile hammer because of the ramped bolt carrier

 

[mike4]

It might be useful for LaRue to add a specific warning to their product description as you suggest, just to avoid people ordering the wrong part. I emphasis wrong part; I'm not trying to be harshly critical, just stating objectively, this is a matter of ordering the wrong part for the application. If you are assembling a weapon from independent parts, it's on you to know and understand the mechanics involved.

The trigger is now a used part, and 9mm ARs stress the hammer even with a perfectly functioning weapon. I would not expect or ask LaRue to accept a return. It is still usable for you subject to your ability to inspect for damage, but it's a firearm trigger (stating obvious) with associated liability thus no longer resellable by them. (Although I doubt you damaged the trigger in one outing given the steel they use.)

Info to potentially help in setting up your lower with a compatible trigger group:

I'm not familiar with variations like lowers accepting Glock mags. I only know the original Colt pattern AR design, in its later form after they addressed some previous design issues with improvements to the underside bolt carrier contours. I built a mostly Colt 9mm upper (every part but the 3 lug barrel) that I wanted to use on both pistol and SBR lowers.

I equipped both lowers with "M16 contour" hammers that have a smooth radius where the BCG drags across the hammer to recock it, which is what you need for the Colt 9mm system. Most 5.56mm semi-auto triggers had sort of a raised rectangle where the hammer strikes the firing pin, resulting in a notch on the upper front face of the trigger. You can look up WMD brand NiB-X semi-auto trigger to see an example of correct contour; this is the actual brand and part I changed out in my lowers several years ago.

The LaRue trigger shape looks even more seriously not compatible. (I have 3 of them in 5.56mm ARs.)

The Colt 9mm direct blowback system also transmits a lot more shock into and down the hammer, so Colt went to using an apparently stronger stainless steel hammer pin to avoid breaking pins. The Colt parts can be difficult to find, KNS Precision also makes stainless pins.

Speaking of hard to find Colt 9mm parts reminds me, hopefully you are good to go on two other lower receiver issues but just in case or for others considering setting up a lower for Colt 9mm AR... you want to use a heavier 9mm weight buffer, a standard carbine/M4 recoil spring, and a spacer that fits at the back of the spring to slightly reduce 9mm BCG travel. Some people stack quarters at the back of their receiver extension, but the proper solution is fairly cheap, slightly lighter, and much easier to disassemble and keep track of (the spacer is retained in the back of an in-spec recoil spring). Colt 9mm Receiver Extension Spacer P/N SP400211, seems to be sold very few places, but G&R Tactical has them for $9.

If you have a design that locks back on an empty mag (I have a drop-in Hahn magwell that does not lock back), that spacer is essential to avoid beating the crap out of the bolt catch.

 

[marvin02]

Here is a great site for info on AR9s:

All Articles

Visit the post for more.

blowback9.wordpress.com

Rise Armament has some nice AR9 specific triggers

 

[Ark]

Don't RMA. Put it on the shelf. Let it call to you. "Heyyy buddy, remember me? Be a shame to let me sit here forever with no lower..."

 

[92FSTech]

I have an MBT2 in my CMMG radially-delayed 9mm build, and have had zero issues with it over thousands of rounds. That said, the CMMG system has a lot more in common with a traditional 5.56 DI bolt carrier than a straight blowback rifle, so that may be a factor.

I wouldn't send it back...keep it and put it in a different rifle. They're great triggers.

 

[shootersix]

There are companies that make pcc triggers some even model specific (trigger tec) my pcc (fx9) has a rise armament 140 and I s flawless, my buddy has the same gun, and the same trigger and his overrode the bolt,

My owner manual says don’t change the trigger, but the owner of the company has a hyperfire and I know a few others in the company have changed to all kinds of triggers, except the trigger tec! They didn’t consult with freedom, they just made the trigger, so freedom bought one, tried it out, and had problems with it!

Drop in trigger groups can be troublesome to ar9’s!

 

[bwframe]

I haven't followed the PCC thing in recent years. When I put mine together for USPSA, I started with a Geissele two stage. Quickly found out the two stage wasn't optimal for the fastest splits. Hyperfire was a big player in the competition world back then and I put one in. It worked well.

Hyperfires go on sale occasionally from outfits like JoeBobs. I picked up another on sale for $100 after using the original for a season of USPSA PCC.


.

 

[Cameramonkey]

I wouldn't send it back...keep it and put it in a different rifle. They're great triggers.

My only 223 AR already has a MUCH better trigger in it. It would be a downgrade.

 

[Cameramonkey]

It might be useful for LaRue to add a specific warning to their product description as you suggest, just to avoid people ordering the wrong part. I emphasis wrong part; I'm not trying to be harshly critical, just stating objectively, this is a matter of ordering the wrong part for the application. If you are assembling a weapon from independent parts, it's on you to know and understand the mechanics involved.

The trigger is now a used part, and 9mm ARs stress the hammer even with a perfectly functioning weapon. I would not expect or ask LaRue to accept a return. It is still usable for you subject to your ability to inspect for damage, but it's a firearm trigger (stating obvious) with associated liability thus no longer resellable by them. (Although I doubt you damaged the trigger in one outing given the steel they use.)

It has a total of 5 rounds on it. Still looks brand new with no blemishes. Not even on the hammer face. Plus I still have the packaging and extra trigger spring. No problems reselling it.

 

[bwframe]

My only 223 AR already has a MUCH better trigger in it. It would be a downgrade.

Our old friend rhino keeps sending me txt's about Primary Arm's and Palmetto having stripped lowers at great sale prices. Just sayin'...

 

[JEBland]

I don't have a PCC AR but Monty went in to design an improved hammer for them if you're willing to go single stage and not cassette trigger:
https://centurionarms.com/triggers/enhanced-pcc-hammer/

 

[DadSmith]

Unfortunately, my only other dedicated 223 lower already has a Timney mid grade trigger. I'm sure since I have all the packaging and its still LNIB an RMA will be issued. At least I hope. (given their reputation, I assume they will make it right since its not documented)

If they don't I think of you put it on the classifieds it will sell. I really like LaRue triggers, and I'm sure there are others as well.

 

[G19G26]

My G2-e works everytime