View Full Version : LaRue MBT Trigger Problem
Hi,
Just installed a brand new Larue MBT trigger group on a brand new Daniel Defense DDM4.
What's happening is it seems to hang up on the first stage and not allow hammer to drop when in semi.....
Does even seem to always give a first stage when it does fire......
When it hangs if I switch to safe then back to semi it fires. But about 1 out of 10 times the trigger feels locked up; no movement at all....Feels like the hammer goes down to far....
Looks right to me...
67312
Second install feels smoother but here's what's happening
If I keep pressure on the trigger preventing itr from resetting then let off it does not reset. I have to manually push the trigger forward to get it to reset....
This aint right....
Second install feels smoother but here's what's happening
If I keep pressure on the trigger preventing itr from resetting then let off it does not reset. I have to manually push the trigger forward to get it to reset....
This aint right....
You are experiencing interference with your ambi safety lever.
If you read the directions that came with the trigger you will see it is designed to work with MILSPEC safeties only.
As it is now, it is not safe and the trigger can release by operating the safety.
You are experiencing interference with your ambi safety lever.
If you read the directions that came with the trigger you will see it is designed to work with MILSPEC safeties only.
As it is now, it is not safe and the trigger can release by operating the safety.
It was just the trigger failing to reset. It would stay back. The selector DD uses is Mil spec I'm sure...Ambi. Selecting safe would not allow to fire but reset the trigger
I tried it with the heavier spring and perfect.
Would this indicate anything I should be concerned about?
[EDIT] Is an ambi selector "standard"? The instructions just say "standar"... I can't imagine how a ambi differs aside from the ambi selector...working parts should be the same....
It was just the trigger failing to reset. It would stay back. The selector DD uses is Mil spec I'm sure...Ambi. Selecting safe would not allow to fire but reset the trigger
I tried it with the heavier spring and perfect.
Would this indicate anything I should be concerned about?
Ambi is not Milspec. Please proceed with EXTREME caution.
I had to put a non ambi safety in mine in order for it to be safe and function as designed.
I’d hate for something terrible to happen.
Your hammer spring is installed wrong(the legs should come from the bottom not the top). Could be causing issues and your trigger pin will walk.
Ambi is not Milspec. Please proceed with EXTREME caution.
I had to put a non ambi safety in mine in order for it to be safe and function as designed.
I’d hate for something terrible to happen.
Thanks but aren't ALL triggers designed for standard milspec to begin with?
I'm curious how the working part of the ambi is different from the standard selector?
I think switching the selector simply released some pressure and allowed the trigger to reset. It would NOT allow it to fire in safe position. So it performs its function.
I'll order up a standard one though and maybe try the lighter spring.
One good thing is the first install took 15 minutes and the third about 5 minutes! SO I know how to do it now!
Oddly the hammer spring came installed backwards...I'm 100% sure it's properly oriented and matches all the literature and photos I can find.
Thanks again...
Any other thoughts more than welcome! If going BANG at the wrong time is even a remote possibility I'd like to cover all bases!
67313
It needs to look like this.
You have the legs of the hammer spring holding active tension on the trigger pin and it won't walk.
It's common for lotsa folks to do it, I hear about it through light primer strikes and walking/lost pins. Easy mistake to make if you don't know about that.67314
Your hammer spring is installed wrong(the legs should come from the bottom not the top). Could be causing issues and your trigger pin will walk.
Yes!
I caught that! It came installed that way and first try was like that.
Thanks!
Hopefully you get it squared away.
The barrel on ambi’s is larger than that of a Milspec non ambi. It presses down on the long LaRue trigger housing, creating the issue.
Install a Colt or other non ambi safety and your issues will be resolved.
While the hammer spring is installed incorrectly, it has nothing to do with your trigger issue.
iflyskyhigh
02-12-22, 21:20
Those triggers work with a variety of safeties. I have them in use with ambi safeties and they function correctly. I have one in a S&W MP 15-22 with an ambi safety and it functions correctly. That gun is for sure not milspec.
I’m sure there are some safeties that will cause issues. Kind of the deal with mix and match AR’s.
FWIW, I have an MBT in SOLGW lower with a Radian short throw ambi safety, and everything works perfectly.
I have to disagree that the hammer spring isn't the issue. It has less force. Until it's installed correctly you can't rule it out.
I run my MBT's with ambi safety's without issue.
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iflyskyhigh
02-12-22, 21:30
The barrel on ambi’s is larger than that of a Milspec non ambi. It presses down on the long LaRue trigger housing, creating the issue.
Install a Colt or other non ambi safety and your issues will be resolved.
While the hammer spring is installed incorrectly, it has nothing to do with your trigger issue.
This just doesn’t sound right to me. If the barrel was bigger you wouldn’t be able to slide it in the opening.
I don’t know for a fact that this is never true, but it’s for sure not always true.
I’d have to go measure my safeties with an outside dial mic which I’m not going to because everyone works as intended.
iflyskyhigh
02-12-22, 21:32
I have to disagree that the hammer spring isn't the issue. It has less force. Until it's installed correctly you can't rule it out.
[emoji1312]
Eliminate the know issue first.
Change/fix one thing at time.
I have to disagree that the hammer spring isn't the issue. It has less force. Until it's installed correctly you can't rule it out.
It's weird how the springs are. Here's the original which is same as heavy Larue, compared to the lighter Larue.
See how it is impossible as far as I know to get any force on the hammer with the legs coming from under the coil.....As it is it's in the cocked position and wont move the hammer.....That's why I had it in wrong to get some force on it. I redid it correctly with the heavier spring which makes sense....
Please see photo
67315
The little leg of the hammer spring goes behind the hammer not in front.
Look at the picture I posted. I edited the post with yours, look at where they go. I'll try and get a pic w/ hammer down if need be.
I'm running an MBT 2 stage trigger in conjunction with an ambi Noveske STS safety in a BCM lower with no problems. I agree that you should fix the hammer spring first and take it from there. It may not be the problem, but don't make any decisions based on an incorrect installation.
The little leg of the hammer spring goes behind the hammer not in front.
Look at the picture I posted. I edited the post with yours, look at where they go. I'll try and get a pic w/ hammer down if need be.
Right!
I think the culprit is a weak spring. Sorry my first photo was the WRONG way but corrected and same problem. Heavier spring installed properly and it's been flawless.
I'll work it tomorrow and if I can have some confidence on safety take it to the range. Private range out in the hills with no one around!
I'll see about that standard selector as well!
Here's how it's installed now.
67316
Thanks!
You might clean it up some. A dab will do you. Install looks right now
You might clean it up some. A dab will do you. Install looks right now
Yea!
I was lubing everything as the issue felt gritty like metal on metal.
Thanks!
It's weird how the springs are. Here's the original which is same as heavy Larue, compared to the lighter Larue.
See how it is impossible as far as I know to get any force on the hammer with the legs coming from under the coil.....As it is it's in the cocked position and wont move the hammer.....That's why I had it in wrong to get some force on it. I redid it correctly with the heavier spring which makes sense....
Please see photo
67315
The top one is a hammer spring, the bottom one is a trigger spring. Are you mixing these up?
The little leg of the hammer spring goes behind the hammer not in front.
Look at the picture I posted. I edited the post with yours, look at where they go. I'll try and get a pic w/ hammer down if need be.
This.
crosseyedshooter
02-12-22, 23:57
The top one is a hammer spring, the bottom one is a trigger spring. Are you mixing these up?
The MBTs I’ve used come with only one hammer spring and two trigger springs. I hope you’re not trying to install a trigger spring on the hammer.
Ambi is not Milspec.
I’m not saying that his safety/selector will work with his trigger, because I don’t know that, but ambi selectors are, in fact, “milspec”. The M4A1 has them. Nobody seems to know this, because as far as I know, Colt sells their commercial rifles, including my 6920s with the older, non-ambi version. Sorry to be pedantic.
crosseyedshooter
02-13-22, 09:15
I’m not saying that his safety/selector will work with his trigger, because I don’t know that, but ambi selectors are, in fact, “milspec”. The M4A1 has them. Nobody seems to know this, because as far as I know, Colt sells their commercial rifles, including my 6920s with the older, non-ambi version. Sorry to be pedantic.
The issue with the MBT is the width of the trigger is on the high end of some spec. Some safety selectors that are cut to the low end aren’t wide enough to clear the width of the trigger. This is also why the MBT rubs against the trigger hole of some receivers. The three MBTs I have work fine with the original Battle Arms ambi safeties as well as a Magpul/Noveske ambi safety. It doesn’t have anything to do with the extra lever on the right side.
The top one is a hammer spring, the bottom one is a trigger spring. Are you mixing these up?
Sorry...
I posted way after I should have knocked off for the day...sorry for the confusion....
You're correct and I don't know how I imagined that was a hammer spring....kinda obvious when you look at them.
I don’t doubt that you are correct. I’m just saying that military rifles come with a ambi selector. I can’t say much about non-milspec selectors, ambi or not.
The issue with the MBT is the width of the trigger is on the high end of some spec. Some safety selectors that are cut to the low end aren’t wide enough to clear the width of the trigger. This is also why the MBT rubs against the trigger hole of some receivers. The three MBTs I have work fine with the original Battle Arms ambi safeties as well as a Magpul/Noveske ambi safety. It doesn’t have anything to do with the extra lever on the right side.
I’m not saying that his safety/selector will work with his trigger, because I don’t know that, but ambi selectors are, in fact, “milspec”. The M4A1 has them. Nobody seems to know this, because as far as I know, Colt sells their commercial rifles, including my 6920s with the older, non-ambi version. Sorry to be pedantic.
Agreed.........I've run into this issue before with MBT's and it was with an ambi safety. I don't know what LaRue means when they say Milspec, I assumed, based on my experience, it meant a single lever, because when I used a single lever Colt safety my issue was resolved.
As evidenced by others in this thread, that may not be 100% accurate. I've not used all models of ambi safeties, let alone with MBT triggers. G-Triggers are my go-to and normal for me is a non ambi, usually Colt LPK, safety.
Regardless, if this is indeed the issue OP is experiencing, it is unsafe and could potentially result in the release of the trigger by manipulation of the safety lever.
I'm not saying it won't work, I'm just saying that is the FIRST thing I would check out, since there is the potential for an AD and all the badness that could come with such an event.
ETA: I also wasn't willing to buy up every ambi-safety on the market to find out the extent of the issue. I found something that worked and left it alone.
Both springs are now installed correctly, and it’s working properly (with the heavy spring)?
If the standard spring is installed, I expect the same results will be observed.
I can't really comment on the Ambi thing other than to say some colts come with em. I use a "modern" colt safety so I can run it on the right side.
But correct installation is paramount for function and reliability in anything from a trigger to an intake manifold or light pole.
joedirt199
02-13-22, 17:05
I have ambidextrous safeties on all my ARs and have 8 MBTs. No problems with any of them. I use the heavy trigger spring on the gaming guns for faster/stronger reset and the lighter one of the precision guns.
Took it to the "range" out in the desert and couldn't make it malfunction. Ran flawlessly. Of course I ran it dry ~100 times before I went live fire.
Still not sure what it could have been and lean towards to weak a trigger spring as it wouldn't reset. New trigger I like to press a little longer to get a feel of the reset. Nice and crisp with the heavy spring. Failed to reset 100% of the time with light spring once I figured out the reset was the issue!
Thanks for your help everyone!
I spoke with LaRue about this issue. They suggested the light spring can have this issue when dry fire but the forceful cycling of the BCG in live fire will force reset and eventually it will break in and be able to reset with dry fire yanking the charging handle.
They also stood firm on built for "standard milspec selector" I brought up the idea about ambi-selector being milspec on some and the idea non-milspec would vary that much from milspec and they stood by their assessment that ONLY milspec single side selector will "work". Sounded like lawyerese as they seemed to shrug shoiulders when I claimed 200 flawless dry and live fires....
I am not sure about the theory of a weak spring. I think the problem was due to the springs installed incorrectly. Now that they are installed correctly you should have no problems.
I have seen some aftermarket triggers not reset right until worked a few times.
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