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View Full Version : AR CMMG trigger report **UPDATE**


savasyn
09-13-2008, 4:58 PM
Update below original post.
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As it turns out, the CMMG trigger I installed in my lower didn't quite do what it was supposed to. It released as expected, but if you gently let pressure off when testing the disconnector, it would release the hammer rather than hand it off to the sear. This is bad. So...
Bottom line for anyone installing a CMMG trigger, please verify beyond a shadow of a doubt that the disconnector to sear hand off is working properly!

Make sure you test by pulling the trigger and while keeping the trigger back, push the hammer all the way back down, hooking it on the disconnector. Then gently release tension on the trigger and see what happens. If the hammer releases = bad, if it hands off to the sear = good. I recommend testing it numerous times to verify proper functionality. We found that releasing the trigger rapidly would cause the hammer to hand off properly, but that's not generally how people actually use the trigger.


Here's a picture of my trigger in case something was installed backwards(as of this edit, it has been determined that it was all in there correctly), I kept the picture large so you could see all the detail:

http://www.stuff2see.net/images3/CMMGTrigger1.jpg


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UPDATE 9/26/08

I'm very happy to report that the new trigger I just received from CMMG today has been installed, tested and fired with complete success!! I want to thank CMMG for not quibbling about replacing the trigger, even it had been slightly machined while in my care.

What's interesting to me is that while this one functions perfectly, it doesn't feel quite as crisp as the first one. Maybe that one felt so good because it was on the "too light to function right" side of things. Oh well, the new trigger is still 200% better then the crappy stock one it replaces! I'll probably have to fiddle with the set screws a little more, but they are really close as is.

I took the opportunity to also install the 2nd Gen CMMG oversized anti-rotate pins. This was mostly for piece of mind as the 9mm uppers are notorious for battering hammer pin holes.

I initially used the stock pins figuring it might have to come out again, but it functioned tested perfectly right from the start. I then added the new pins and retested, again with perfect results. Of course, this was my experience of the first one, too, but I tried numerous things this time to get it to fail, but it never did :)

Not wanting to wait, I took it down to the range to try it out. Learning from my previous experience, I loaded one round and fired. That worked. Then I loaded two rounds and tried again. No problem again. I went through the first 25 rounds in sets of 3s and 5s expecting it to fail at any time, but nope, it worked perfectly all the way through(you know, like you'd hope it would!!)

Feeling confidant, I loaded the last 25 up in the mag and this time actually bothered to shoot at the target. I must say, I'm pretty happy with the results. Here's the target from the 2nd 25, shot fairly rapidly off-hand with fogged up glasses(it was WAY hot in that range!) at 25 yards. I'm sure with a little patience, I could have gotten all 25 of them in the bull, but I'll take it :)

(note: the two holes at the top are from the target hanger)
http://www.stuff2see.net/images3/target.jpg

Lastly, I know my initial post had a lot of people question the reliability of these triggers and hopefully this and the posts from other happy users will help on the road to restoring the faith.

technique
09-13-2008, 5:06 PM
WoW sounds fun. Is it something to do with the 9mm bolt? What hammers work well in 9mm builds? I thought you were limited on what you could use. Thats why they make 9mm hammers.

savasyn
09-13-2008, 5:10 PM
No, it has nothing to do with the upper, the trigger is clearly not doing what it's supposed to be doing.

This hammer does work just fine with the 9mm bolt. The problem they have with the RRA-style notch topped triggers is that they jam the bolt to the rear.

6079Winston
09-13-2008, 5:11 PM
I thought 9mm hammers were different also. You might want to take the offending parts out of the lower too, just to be on the safe side. Don't panic, I'm sure Randall will chime in soon.

technique
09-13-2008, 5:23 PM
This is what a custom 9mm bolt that works with standard hammers/match triggers looks like.

http://i285.photobucket.com/albums/ll42/technique408/9mm002.jpg

gunrun45
09-13-2008, 6:09 PM
I thought CMMG (along with RRA) said NOT to use their match triggers in pistol caliber builds.
CALL THEM.

technique
09-13-2008, 6:15 PM
I thought CMMG (along with RRA) said NOT to use their match triggers in pistol caliber builds.
CALL THEM.

They do say that. That is why I had th RRA bolt pictured above done. So I didn't have to swap hammers when I put my 5.56 upper back on.

I agree, Call them.

savasyn
09-13-2008, 6:39 PM
This is what a custom 9mm bolt that works with standard hammers/match triggers looks like.

http://i285.photobucket.com/albums/ll42/technique408/9mm002.jpg

Interesting, I didn't see anything about not using the CMMG tigger with pistol cal uppers.

Anyway, like I said This malfunctions doesn't seem to have anything to do with the upper, you can recreate the problem with no upper installed at all while function testing.

Technique, do you have the specs on how to ramp the bolt? I'd like to get that done to mine anyway and Randall doesn't have the specs for it.

Speaking of him, I'm actually heading out the door in a few minutes to have him take a look at the trigger problem.

technique
09-13-2008, 6:44 PM
Interesting, I didn't see anything about not using the CMMG tigger with pistol cal uppers.

Anyway, like I said This malfunctions doesn't seem to have anything to do with the upper, you can recreate the problem with no upper installed at all while function testing.

Technique, do you have the specs on how to ramp the bolt? I'd like to get that done to mine anyway and Randall doesn't have the specs for it.

Speaking of him, I'm actually heading out the door in a few minutes to have him take a look at the trigger problem.

M24armorer, He has them, He can swap you or do yours.

EBR Works
09-13-2008, 7:22 PM
The hammer spring on mine was installed backwards from the factory. :kest: Yours appears to be correct. I reversed the spring and just installed it yesterday and have not fired it yet. Function check on mine is correct. I'll head out to the range tomorrow with .223 and 7.62x39 uppers to give it a shakedown.

http://i59.photobucket.com/albums/g302/impactco/cmmg1.jpg

caduckgunner
09-13-2008, 8:10 PM
Ummm...... I have one of these on the way.

aplinker
09-13-2008, 8:15 PM
These triggers are manufactured different than std AR triggers. The malfunction he sees has nothing to do with it being 9mm - especially since the malfunction occurs manually, without an upper.

bonjing
09-13-2008, 8:54 PM
M24armorer, He has them, He can swap you or do yours.


sorry to go off topic here, but will the RRA 9mm hammer work with a ramped bolt? the ramped bolt puts less wear and tear on the trigger group and trigger pin holes right?

apbrian112
09-13-2008, 9:18 PM
9mm hammer will work with a ramped bolt... it'll also work with regular ar15 hammers too, which is why people ramp their bolts...

till44
09-13-2008, 9:26 PM
Sounds like fun...I don't see a problem! Have fun with it.

dfletcher
09-13-2008, 9:51 PM
I had the same problem with the Jard trigger. May have been my fault in adjusting the set screws, I really don't know. But I ended up figuring the hell with it, went with the 2 stage RRA and have been very happy.

savasyn
09-13-2008, 11:31 PM
Ummm...... I have one of these on the way.

Give it a try, just make sure you check it fully before use. Oh yeah, and only load 2 rounds in the first mag you try.

Mine might be a fluke. I'll take to CMMG on monday.

savasyn
09-13-2008, 11:35 PM
Ok, I'm back from Randall's. He spent a while playing with it and ended up taking of .0015" off the disconnector shelf trying to get more engagement. Alas, the final result was that it had a less than desirable result on the overall feel of the trigger while not fixing the problem anyway.

He put the stock unit back in and man does it feel heavy and lame in comparison, but I know it works correctly.

Hopefully CMMG can offer some insight and as I bought the trigger directly through them, perhaps they'll take it back.

ar15barrels
09-13-2008, 11:54 PM
Ok, I'm back from Randall's. He spent a while playing with it and ended up taking of .0015" off the disconnector shelf

0.015"

M. Sage
09-14-2008, 12:33 AM
Lol, yeah. .0015 wouldn't be a lot of material. :p

Bowser
09-14-2008, 12:41 AM
I have a CMMG LPK and am going to be using the RRA upper assembly for a 9mm build. Should I still check for this?

tenpercentfirearms
09-14-2008, 7:36 AM
Ok, I'm back from Randall's. He spent a while playing with it and ended up taking of .0015" off the disconnector shelf trying to get more engagement. Alas, the final result was that it had a less than desirable result on the overall feel of the trigger while not fixing the problem anyway.

He put the stock unit back in and man does it feel heavy and lame in comparison, but I know it works correctly.

Hopefully CMMG can offer some insight and as I bought the trigger directly through them, perhaps they'll take it back.

They should take care of it by sending you another one. If they don't, then that is quite concerning.

EBR Works
09-14-2008, 7:40 PM
OK, got out today to try this trigger in my Stag lower paired with a DPMS 7.62x39 20" upper. Function was absolutely flawless and I had the take up and over travel screws adjusted per factory instructions which gave me a crisp single stage break that felt like about 3-4 lbs. I really like this trigger better than the RRA two stage in my carbine. Definitely worth the money IMO.

a1fabweld
09-14-2008, 9:47 PM
I fired 100rds today (.223) with my newly installed CMMG trigger & it funtioned flawlessly. Not one problem to speak of. With my limited knowledge, I found that the slightest adjustments of the overtravel screw (rear) make a big difference in the way the hammer catches. I hope I said that right? I'm sure CMMG will handle you on the situation being that this is a new item & bad reviews would make an awful impact on these trigger sales. Maybe send your lower to them & have them replace/adjust it at their facility? Best of luck.

savasyn
09-14-2008, 10:12 PM
Awesome! I'm very glad to hear that mine might be an anomaly. I'll be calling them tomorrow to see what we can work out.

savasyn
09-15-2008, 10:11 AM
As a follow up to this, I just got off the phone with CMMG and they are sending me a replacement trigger tonight. We'll see how it goes...

Eric_Oh
09-15-2008, 11:21 AM
keep us posted. I"m sure alot of us had these slated for current & future projects. I know i did(*edit* do.).

savasyn
09-15-2008, 11:27 AM
After discussing it with Randall, it is possible that my Olympic Arms lower is just out a spec enough that that model of trigger might never work right in it.

As there aren't any new Oly lowers in CA these days, it might be an isolated case. That said, it's obviously still a good idea to thoroughly function check any new trigger before trying live ammo, and then with only 2 or 3 rounds in the mag.

The biggest mystery for me is that I DID check the trigger multiple time before going to the range the first time so I do not know how I missed the failure.

Army
09-15-2008, 1:08 PM
Check the disconnector spring. If worn or crushed, it will not have enough pressure to keep the disconnector engaged.

ar15barrels
09-15-2008, 2:32 PM
Check the disconnector spring. If worn or crushed, it will not have enough pressure to keep the disconnector engaged.

Disconnector spring had LOTS of tension.

aplinker
09-15-2008, 2:44 PM
lay your stripped Oly on top of your OLL and see if the trigger pin holes line up - though it will probably be tough to tell.

I'd wondered if you were using it in your old lower (karma since we can't have them :D :p)

I'll be interested to hear if the new one has the same issue... if it does, be sure to swap it to your OLL.

Disconnector spring had LOTS of tension.

Did you try therapeutic massage?

ar15barrels
09-15-2008, 2:48 PM
Did you try therapeutic massage?

It jumped out and hit the floor a couple times during removal and assembly.
Is that theraputic?

savasyn
09-15-2008, 2:49 PM
I do have a 2nd stripped lower that's been sitting in the safe for close to a year so if it doesn't worked in the Oly, it'll go in there.

I'd really like the new one to work in my Reg'd rifle as it solves a number of issues all at the same time.

savasyn
09-15-2008, 2:51 PM
It jumped out and hit the floor a couple times during removal and assembly.
Is that theraputic?

I thought the therapy part was sifting through the heap of aluminum shavings looking for the drill bit ;)

Btw, has that one resurfaced yet?

ar15barrels
09-15-2008, 2:52 PM
Btw, has that one resurfaced yet?

Not yet.
It will show up as soon as I place an order for replacements...

aplinker
09-15-2008, 2:55 PM
It jumped out and hit the floor a couple times during removal and assembly.
Is that theraputic?

doesn't yet sound like a happy ending.

lakai
09-15-2008, 8:46 PM
wow your lower sure has a crappy finish it looks like its forged from concrete!

savasyn
09-15-2008, 9:39 PM
wow your lower sure has a crappy finish it looks like its forged from concrete!

It's actually not as bad as the picture shows. Due to the nature of macro photography and my haste to get the picture, I ended up with a very shallow depth of field. As such, I had to process the hell out of the image to get the parts I wanted visible, this included multiple heavy sharpening passes which made it appear to have that texture. In reality, it looks like any other lower.

savasyn
09-15-2008, 9:44 PM
I have a CMMG LPK and am going to be using the RRA upper assembly for a 9mm build. Should I still check for this?

Yes, you should definitely fully function check any new trigger before installing any upper or loading the weapon. If it checks out manually(most will) then proceed to the range, but I recommend only loading 2 rounds the first few times just to be extra safe.

The problem I had was completely independently of the upper assembly, it was purely in how the various parts of the trigger failed to interact correctly. As far as I could tell, the trigger worked just fine with the RRA 9mm upper.

ar15barrels
09-15-2008, 10:31 PM
wow your lower sure has a crappy finish it looks like its forged from concrete!

Doesn't matter.
It's a registered AW.
More than can be said for most people's lowers... ;)

I have one that looks just like it.
It's registered too.

How many RAW's do you have?

ETA: I own your page two.

caduckgunner
09-16-2008, 6:01 AM
I got mine in the mail yesterday. I installed it last night, and it feels great and dry functions fine. I agree that it was kinda scary with the 2 screws installed, a very light weight single stage

lakai
09-16-2008, 11:19 AM
It's actually not as bad as the picture shows. Due to the nature of macro photography and my haste to get the picture, I ended up with a very shallow depth of field. As such, I had to process the hell out of the image to get the parts I wanted visible, this included multiple heavy sharpening passes which made it appear to have that texture. In reality, it looks like any other lower.

hehe the finish looks like that you find on standard triggers kinda.

lakai
09-16-2008, 11:20 AM
Doesn't matter.
It's a registered AW.
More than can be said for most people's lowers... ;)

I have one that looks just like it.
It's registered too.

How many RAW's do you have?

ETA: I own your page two.

Huh ? What the hell does that have to do with anything?

ar15barrels
09-16-2008, 11:52 AM
Huh ? What the hell does that have to do with anything?

In response to this:

wow your lower sure has a crappy finish it looks like its forged from concrete!

WTH does THAT have to do with anything either? ;)

lakai
09-16-2008, 1:57 PM
In response to this:



WTH does THAT have to do with anything either? ;)

lol

It doesn't matter

grammaton76
09-16-2008, 6:53 PM
I thought the therapy part was sifting through the heap of aluminum shavings looking for the drill bit ;)

Btw, has that one resurfaced yet?

Aluminum shavings plus probably-steel bit seems to me a good time for one of those Harbor Freight 250lb magnets to come out to play. They're cheap and infinitely useful.

savasyn
09-16-2008, 8:03 PM
Aluminum shavings plus probably-steel bit seems to me a good time for one of those Harbor Freight 250lb magnets to come out to play. They're cheap and infinitely useful.

I vied for the magnet but we ended up doing it by hand. He works on steel/iron as well so we would have been pulling a lot of useless carp off the magnet after the fact. An Elecrto-magnet would have been key, turn it on to pull all of the iron out of the aluminum then turn it off to clean.

grammaton76
09-17-2008, 1:14 PM
I vied for the magnet but we ended up doing it by hand. He works on steel/iron as well so we would have been pulling a lot of useless carp off the magnet after the fact. An Elecrto-magnet would have been key, turn it on to pull all of the iron out of the aluminum then turn it off to clean.

Eh, swarf comes off of the 250lb magnets pretty easily. After an AK build or two, my magnet's covered in the stuff (I use it to clean the shavings off of the carpet before they get embedded). :)

a1fabweld
09-17-2008, 7:24 PM
This threads pretty much done as we are talking about how to collect magnetic chips & rid our carpets of metal shavings.:sleeping:

savasyn
09-26-2008, 3:55 PM
This threads pretty much done as we are talking about how to collect magnetic chips & rid our carpets of metal shavings.:sleeping:

It's alive again(at least momentarily) as I just posted an update which can be found in the first post of this thread.

EBR Works
09-26-2008, 6:39 PM
I have been to the range with mine 3x and no issues. Much better than my RRA NM triggers IMHO :D

a1fabweld
09-26-2008, 9:43 PM
Maybe a moderator can change the title to something a little more friendly?:)

ar15barrels
09-26-2008, 9:48 PM
Maybe a moderator can change the title to something a little more friendly?:)

The OP can change it too... ;)

savasyn
09-26-2008, 10:34 PM
Maybe a moderator can change the title to something a little more friendly?:)

What would you like, I'm taking requests :D

a1fabweld
09-27-2008, 9:15 AM
I'm not trying to be a smart azz just in case anyone thinks so, but to me, the title sounds like "beware of CMMG triggers". Maybe call the thread " CMMG trigger report or something a little softer. That is if you are happy with your results which I take it you are. After all, this is YOUR thread. :)

savasyn
09-27-2008, 10:08 AM
I'm not trying to be a smart azz just in case anyone thinks so, but to me, the title sounds like "beware of CMMG triggers". Maybe call the thread " CMMG trigger report or something a little softer. That is if you are happy with your results which I take it you are. After all, this is YOUR thread. :)

Yup, that's what I changed it to last night.

And yes, I WAS saying "beware of CMMG triggers" in my initial post given the nature of the failure I experienced. I'm very happy that the problem I had seems to have just been that specific unit.

tenpercentfirearms
11-03-2008, 6:21 AM
I finally got mine, installed one in my RRA 9mm build, and shot it Saturday. Not a single problem.

I agree, I tried doing the "advanced" install and it was a whole different trigger. It basically turned into a single stage. I have no problems with a two stage so I took the screws back out and just left it as is.

If you want a nicer trigger in your 9mm build or just a nicer trigger, the CMMG works and works well!

a1fabweld
11-03-2008, 9:34 AM
I like my first CMMG trigger so much, I have another coming for a different build.

Jim_KT
05-10-2009, 10:39 PM
I agree, I tried doing the "advanced" install and it was a whole different trigger. It basically turned into a single stage.


Thread revival!

Anyone else have the same results? I just installed a CMMG 2-stage trigger and performed the advanced install (using the allen screws). Results were the same as 10%'s.