Need to know what AR triggers work well in CMMG build?

[2Wheels4Ever]

I run that PSA 3.5lb drop in unit on a dedicated CMMG upper. Works flawlessly. Great trigger for $90.

 

[kmk1012]

Yes to both

So, does the dedicated upper from CMMG have a barrel designed for .223 dia bullets unlike the .224 of the center fire brothers? Also, does the CMMG upper require the chamber adapter that is used on the conversion kits? I've never looked at them.

 

[FATAL125]

Would the reduced springs not cause more striking issues? Or is that to aid in cycling?

Sorry everyone I completely left out that this is a 22lr upper.

Current issues are not cycling issues. Striking issues. I'll get click, rack CH, check case, 0 marks on rim. At times I can run the trigger fast and get a handful of bangs in a row. If I go slow, definitely no bang, no rim mark.

Ill swap the thing around on other SBR lowers to see if the other triggers I got help.

It doesn't cause any light strikes for me. I installed just to get the PSA pull weight down a bit. Wasn't sure it'd work, but I've yet to have a problem.

 

[FATAL125]

So, does the dedicated upper from CMMG have a barrel designed for .223 dia bullets unlike the .224 of the center fire brothers? Also, does the CMMG upper require the chamber adapter that is used on the conversion kits? I've never looked at them.

The dedicated upper is also a dedicated 22lr barrel. No chamber adapter is required cause its not trying to neck down from a 223/556 chamber.

 

[FATAL125]

Would the reduced springs not cause more striking issues? Or is that to aid in cycling?

Sorry everyone I completely left out that this is a 22lr upper.

Current issues are not cycling issues. Striking issues. I'll get click, rack CH, check case, 0 marks on rim. At times I can run the trigger fast and get a handful of bangs in a row. If I go slow, definitely no bang, no rim mark.

Ill swap the thing around on other SBR lowers to see if the other triggers I got help.

Have you done a thorough clean and lube? Is it possible the firing pin is gummed up and not allowing full movement/contact?

I know mine hates being dirty. Wondering if that may be at least a peice of the issue. Might make sense if you say you can run the trigger fast and get a handful of good strikes.

Edited to add:
I know there are also upgraded firing pins for the CMMG bolt that you can purchase. Not sure on manufacturers or cost, but I remember reading about it somewhere.

 

[Z-PDX]

CMC 2.5lb single stage trigger is 100% in dedicated upper.

highly recommend.

 

[FATAL125]

CMC 2.5lb single stage trigger is 100% in dedicated upper.

highly recommend.

This one right?

CMC TRIGGERS AR-15 TACTICAL TRIGGER GROUP | Brownells

Check out the CMC TRIGGERS available Online at Brownells Today and many more Rifle Triggers & Parts products are available in our Gun Parts Department.

www.brownells.com

If so, I had that on my list for a different build. It hasn't even begun yet, but glad to hear its worth the purchase.

 

[Z-PDX]

This one right?

CMC TRIGGERS AR-15 TACTICAL TRIGGER GROUP | Brownells

Check out the CMC TRIGGERS available Online at Brownells Today and many more Rifle Triggers & Parts products are available in our Gun Parts Department.

www.brownells.com

If so, I had that on my list for a different build. It hasn't even begun yet, but glad to hear its worth the purchase.

that's it.

also… the included pins, while of high quality, were too large in diameter for the receiver. this is apparently not uncommon, and i just set them aside for a later build.

ended up using KNS pins, which i also recommend highly.

 

[Yarome]

I use rise triggers and never had an issue. Typically one of 2 lowers. One has an LE145 (4.5lb) and the other an RA-140 (3.5lb).

CMMG dedicated in a RTB smooth side sportster upper.

 

[Member 34319]

Have you done a thorough clean and lube? Is it possible the firing pin is gummed up and not allowing full movement/contact?

I know mine hates being dirty. Wondering if that may be at least a peice of the issue. Might make sense if you say you can run the trigger fast and get a handful of good strikes.

Edited to add:
I know there are also upgraded firing pins for the CMMG bolt that you can purchase. Not sure on manufacturers or cost, but I remember reading about it somewhere.

It was cleaned and lubricated before stating that days range session.

I'll try the trigger swap first and if still having issues I'll look at strikers.

Thanks

 

[Hueco]

You know me and triggers

My dedicated upper is running great with a Larue MBT. I've grown quite fond of them actually.

May need to see if @Lasers has an in with another big purchase deal.

 

[Hueco]

So, does the dedicated upper from CMMG have a barrel designed for .223 dia bullets unlike the .224 of the center fire brothers? Also, does the CMMG upper require the chamber adapter that is used on the conversion kits? I've never looked at them.

Building a "dedicated" upper means two things:
- the chamber is cut for .22LR (no chamber adapter needed)
- the barrel is around a 1:16 twist (rimfire rotation - a big cause of inaccuracy in conversions is throwing a 40gr rimfire down your 1:7 barrel)

You don't have to buy one from CMMG. Right To Bear has conversion bolts and barrels constantly on sale and Aero does as well for uppers and handguards (or use whomever - point is, it's not that expensive to put together an upper). There's a mag adapter out there that will allow you to use M&P 15-22 mags as well, which retain LRBHO and which I'm a big fan of so that manual of arms between AR and AR22 is the same.

Also, rimfire is the shiz. Especially suppressed.

 

[Member 34319]

rimfire is the shiz

 

[Wombat of Doom]

Hiperfire PDI works in mine. I also had some success with the ALG ACT. I did have some bad luck with a few I tried. Namely the Geissele 3G

 

[Centermass]

I'm the opposite, have 2 that are speed steel guns (ones SBRed) and Hiperfire triggers with the lightest pull springs installed (original line of their triggers) won't reset with .22LR. The hammer spring is too stiff and the round doesn't have the "umph" to reset it. It just short stroked the CMMG bolt. Me and my son both run Geissele S3Gs with very high reliability. My sons has over 15k rounds on it and mine (SBR) is close to 6K. Only issue I've had are broken firing pins (CMMG keeps replacing them). My sons never had that issue.

 

[Hueco]

I'm the opposite, have 2 that are speed steel guns (ones SBRed) and Hiperfire triggers with the lightest pull springs installed (original line of their triggers) won't reset with .22LR. The hammer spring is too stiff and the round doesn't have the "umph" to reset it. It just short stroked the CMMG bolt. Me and my son both run Geissele S3Gs with very high reliability. My sons has over 15k rounds on it and mine (SBR) is close to 6K. Only issue I've had are broken firing pins (CMMG keeps replacing them). My sons never had that issue.

Do the firing pins break at a consistent point?

 

[Yarome]

Do the firing pins break at a consistent point?

The tips kind of fragment and/or break off at the shoulder from the main pin shaft. There are "enhanced" pins available though and of the 3 CMMG bolts we run, all of them have been running without issue with the upgraded pins. Prior to that, I had 2 of the 3 fail and then just ended up replacing them all with the borebuddy firing pins.

 

[Hueco]

The tips kind of fragment and/or break off at the shoulder from the main pin shaft. There are "enhanced" pins available though and of the 3 CMMG bolts we run, all of them have been running without issue with the upgraded pins. Prior to that, I had 2 of the 3 fail and then just ended up replacing them all with the borebuddy firing pins.

Good to know. I'm only about 2k into my first one. Will have to stock some pins so range day doesn't become a bummer.

 

[Centermass]

Yeah, all of my breaks have been at the shoulder. And have also had a couple broken firing pin springs. I don't dry fire my rimfires and my sons rifle has the exact same bolt and trigger and has never had an issue. CMMG has replaced every p8n and spring I've broken and at one point, sent me some extras in case I needed them in a match situation. Zero complaints about the company and their customer service from me, they've been great.

 

[Yarome]

CMMG has replaced every p8n and spring I've broken and at one point, sent me some extras in case I needed them in a match situation. Zero complaints about the company and their customer service from me, they've been great.

This is true. CMMG replaced the 2 I broke... and an ejector... hassle free. We run ours pretty hard so when I finally did a dedicated upper and tossed in some upgrades learned from past experience it made sense to just upgrade the pins, ejectors and spring sets on them all and keep the OEM's as backups.

Pin failure seems pretty random though. I put the same ammo though all of them and use is similar. One pin gave up the ghost just shy of 1k-ish, the second must have had close to 3k on it. I've "read" of others with failures at much lower round counts, but there are so many out there... and you're really only going to hear about the failures, right(?).

I can't "quite" vouch for the borebuddy pins just yet, but one is pushing 3k-ish and the other 2... maybe around half that(?). No breaks and the tips still look new.

Half a thumb up, "looking good so far" is all I got.