I’m a newb at working on these type of guns so I took on what I thought was an easy deal. Installed a cmc trigger, after installing it the rifle won’t cycle at all, every round has to be manually chambered. Any idea whT I might have done? I’ve tried different ammo, same result. It’s the 3.5 lb curved trigger. Thanks from an old man newb

Does the trigger even work? The CMC trigger is a single drop in trigger group so there shouldn't be a problem with extra pins or springs. Maybe a photo would prove enlightening?

Did you use M&P 15-22 trigger / hammer pins or standard AR size anti-walk pins. (there is a difference) If you used standard AR size and cranked down on the screws it could bind things up.

Could be a bad trigger assembly, did you function check it before assembly?

Only time I every had problems with a CMC trigger in a 15-22 is when a leg of the hammer spring broke after 15000+ cycles. (I wore it out )

A slight possibility exists that the interior of the lower rcvr which houses the fire control group (hammer / trigger / safety) is out of spec.

I had that happen on an AR into which I was installing an aftermarket trigger module assembly (Ra-140). I remedied the problem by removing material (approx 1-1 1/2mm) from the sides (about the forward-most 1/3) ( the top edges) and the top edge of the front of the "cassette". Worked great afterward. In my case the trigger would not reset due to the assembly being bound-up within the rcvr. If the assembly is installed to tightly which might be binding the hammer, that could lead to your problem.

I would remove upper from lower and basically do a function check.

Protecting the rcvr where the hammer will impact (or walking hammer forward), cock the hammer and pull trigger. If it "fires" go to next step.

After having pulled trigger and hammer goes forward, keep the trigger pulled back. Cock hammer again and release trigger. The trigger should reset. If it reset correctly, pull trigger again (protect front of rcvr against hammer impact). Hammer should fall as if striking firing pin.

This next test isn't mine but it's good. Disregard any reference to photos. Given that yours is an assembly module, I assume it's assembled correctly though the function principles are the same as a mil-spec trigger.

"It definitely sounds like an FCG problem. My guess the trigger is not returning on release. As long as the trigger is held to the rear, the semi-auto sear (1) engages the hammer (2) when it's cocked to keep it from following the BCG when it returns to battery. This sear will not disengage until the trigger moves forward to it's reset position.

If the trigger is to the rear and the hammer cocked, engaging the safety will push the trigger forward and the semi-auto sear will release the hammer to be engaged by the trigger sear (4) which will release the hammer to fire the weapon when the trigger is depressed. You can test this by seperating the upper from the lower with the hammer in the released position, depress the trigger and hold it while cocking the hammer. Keep the trigger depressed and engage the safety. You will feel the trigger being pressed forward to it's reset as the safety pivots into position. In normal operation, spring pressure will press the trigger forward to it's reset. If the springs are not correctly installed (4&5), or of they are broken or worn, the trigger may not return".

Me again: If it malfunctions doing these tests I'd say most likely it's too tight. Also make sure the safety is atop the rear of the trigger / hammer assembly. Safety switch should be installed with hammer in cocked position.

If the trigger module has set screws and / or you're using aftermarket anti-walk/rotate pins, make sure they're not too tight. That can cause your problem. Snug is all you want.

Not sure if this relates to your issue but the fix was to work the trigger to break it in...

I dropped a CMC trigger in my M&P 15.
I get done, thouroughly test it dry fire, and check operation of the safety selector. All good.

So I head out back to try it all happy. Finally rid of that stock sandpaper grit-trigger.

POW crack off a round, feels good. Pull trigger again, nothing. Trigger is frozen, no movement of any kind. View and check safety, good there, start thinking what I may have done incorrectly during install. Scratch Don't know, the thing is super easy to install.

Try again, trigger releases, POW gun fires. Then same deal, trigger frozen. Keep pulling trigger carefully, after a few seconds of pulling, POW it lights off a round somewhat unexpectedly. eek MAd
Ok now I'm almost scared of the thing. WTH is it going to do next?

So I stop and clear the gun. Take off the upper and start looking over the trigger. Works fine, resets, releases and functions as it should. Put upper back on, trigger works fine through several dry fires. Load a round, POW gun fires and the trigger freezes again.

After some further testing, the trigger is not resetting after you fire a live round. Fire a round, and after a few seconds you hear a 'click'. The trigger has then reset and you're good to go for another shot. This only happens after a live round, but the trigger works fine during testing and dry fires.

I call CMC and get one of the Techs who tells me to try and work in the trigger some more. With the upper removed, cycle the trigger over and over again about 30 or 40 times. Of course I use my thumb to stop the hammer, don't let it fall with the upper off. I did this about a dozen times after intial install so I figured I was ok.

Glad you got it going but goodness, that's pretty cheesy. No CMC for me.

Missed the part where he/she got it going, especially since the OP only has one post. Don't take your gun apart if you don't know what you're doing . . .

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Wisdom comes thru fear . . .

Sorry about that. I was replying to GhostMutt.

That wasn't my issue, i installed a hiperfire 24C, no problems whatsoever, that was copied from another forum from a user who had similar problems. I found it with a quick google search.

If you could post a picture, that MIGHT help; I don't recall my CMC trigger coming with anti-walk pins, and given that the 15-22 has a wider frame than a MIL-SPEC AR15, it is possible... POSSIBLE mind you, that you either didn't put the trigger and hammer pins back in, or they fell out because you didn't realize that they need to be there.

If the housing is indeed firmly attached to the lower receiver, then it would seem an issue with the trigger; breaking it in manually as suggested above MAY work.

I suggest you take it to a semi-competent gunsmith; if he tries to sell you anti-walk pins, ask him to install them (to ensure the correct width for the 15-22).

Good luck!

My CMC trigger did come with anti-walk pins but they were for a proper AR-15 and not wide enough for the 15-22's receiver. They still worked but they were about 1.5-2mm short on either side. I got some KNS 15-22 specific pins to address that.

The trigger 'cassette' should just drop (literally) straight into the receiver so if you had to force it in, in anyway there's a problem.

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The cassette style I "shaved" in an AR just dropped in; no force required etc. What was evidently the issue was where the inside of the lower sides curve to the front, there was no clearance between it and the cassette which evidently is required. Perhaps a 1/1000th or 2. Did what I did and it functioned fine. Before the bit of filing I did on the cassette, I reckon the module was pushed rearward just enough to impact the relationship with the safety (though the switch felt fine) and resulting in a non-reset.

I had the same problem after I installed my CMC trigger. So I changed the extractor for an aftermarket one and now it's a different weapon. Great trigger and the cycling is so much smoother with the new extractor.
I did not make any other alterations to the weapon.

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I have a CMC flat trigger in my M&P 15 Sport II. It works perfectly!
In my M&P 15-22 I have the Hyperfire 24C. It also works perfectly!
Before I had these triggers in these two rifles I had ALG-ACT triggers which also worked perfectly, but wern't as good as the ones I have now.
I think if you are having problems, you should probably remove the triggers and re-install them with the manufacturers instructions. You probably won't have any issues if you do that!

Lol. I violated my quote (memory deal). Didn't even have a clue I had made this statement. Days ago I ordered and received a CMC trigger which goes for 200.00 + at several sites. Going in a side charge build I just did. PA had it on sale from 89.00 and a couple of dollars shipping. Hope it functions. This one: http://www.primaryarms.com/cmc-ar-15...ger-flat-91513

That's not the same trigger I have. I have this one:

CMC AR15 / AR10 Single 1 Stage Drop-in Trigger - Flat Bow | CMC Triggers