Help me figure out why my new LaRue MBT is sticking/doesn't feel right

[gregr507]

So I just installed a MBT in my AR, but am running into issues. I first installed with the heavy spring, but it felt really heavy, like far heavier than I imagine it is supposed to. It also felt gritty. I uninstalled it, greased it, and reinstalled it several times, but kept running into the same issue. Eventually I decided to try the light spring, which feels much better and closer to what I imagine it should be like. However, there still seems to be some grit/resistance during the first stage. Interestingly, I didn't notice it yesterday when I first installed it and though the trigger felt great, but today it feels heavier and grittier.

Another issue is that the trigger does not want to reset on its own, and also is sticking. What I mean is that when I pull through the first stage and approach the wall of the second stage and then let off the trigger, the trigger will stay stuck in that position and will not reset to neutral without me having to push it forward. Then when I try to test the reset, the trigger will stay stuck fully depressed, and will not reset unless I push it forward.

I've uninstalled and reinstalled this thing probably 5 times now (around 4 were with the heavy spring, then the last was the light spring) and keep running into issues. I feel like I am installing it correctly, is there something I am missing? What could be causing this?

Any help or advice is much appreciated

[AKDoug]

Hard to say. Has this lower been used previously and worked properly with another trigger? Have you watched any of the YouTube videos to check your spring orientation, etc? Can you get us any pics so we might spot something?

[gregr507]

Hard to say. Has this lower been used previously and worked properly with another trigger? Have you watched any of the YouTube videos to check your spring orientation, etc? Can you get us any pics so we might spot something?

The lower is a PSA lower that I originally installed the PSA EPT in, and it worked fine. I will get some pics and post in a minute

[AndyLate]

Seriously, contact Larue and swap it out.

Andy

[gregr507]

Here are a couple pics of the trigger installed in the lower, hopefully that helps. Please let me know if there is anything else needed to diagnose the issue!

https://imgur.com/gallery/2O5K2M6

[crosseyedshooter]

I have three MBT-2S triggers, two with light and one with heavy spring. All of them have smooth take-up and no grittiness at all. Something is wrong with yours or it is interfering with the receiver somehow. You could try cleaning it with a blast of brake cleaner and relubing the entire thing, but it should not have grittiness regardless of what you think the pull weight should feel like. Also check if the trigger shoe is rubbing against the receiver in the trigger slot area.

[MistWolf]

Check to make sure the disconnecter spring is installed correctly.

[mark5pt56]

Looking at the second pic, appears that the material in front of the safety body is misaligned. Is it the pic angle or is that portion rubbing?

[Mr McSimon]

What safety are you using? From what I can see it looks like mil spec, which should be fine, but I did have a similar problem with an MBT and BAD-CASS short throw. I had read that there was some grinding and polishing I could do to get them to work together, but in the end, I just ended up installing a Colt ambi safety and everything with the trigger started working properly. Do you have another safety you can try? I have some extras I could help you out with if you don't, just pm me.

[AKDoug]

I honestly can’t see any difference between yours and mine. I think a call or email to LaRue is in order. Do you have another lower you could install it in? Just to check. Here are pics of mine. Difficult to do with a phone. Yes I know the rifle is dirty.


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