Replacement triggers suitable for 9mm blowback dedicated AR?

I've not heard that. Mine has a 3 lb. Velocity trigger in it.
Tuning in to learn more.

I have a Quarter Circle 10 AR-9 carbine with a Rise Sport Trigger @3.5 # trigger pull. At around 1,000 rounds I haven't experienced any trigger issues. I have replaced the buffer and spring though.
I have not heard of issues related to purpose built 9mm blow back and trigger groups either. The problems may come from AR lowers and AR BCG'S modified to shoot 9mm!

I have Rise triggers on 3 AR's, one 9mm and two 223's, no issues!

Smiles,

That’s a new one on me, need to get out more... But Covid

Yes some AR triggers are NOT compatible with the 9mm bolts. I forget which ones right off the top of my head right now. ARFCOM would have better info on what triggers work with 9mm bolts and which ones do not.

I went with this....................works fine, and I always upgrade stock trigger anyway. And its on sale if you need one.

https://www.joeboboutfitters.com/CMC-AR-15-9MM-PCC-Flat-3-5lb-Single-Stage-Drop-In-p/cmc-95503.htm

A lot of guys use the 308 buffer spring without issues.

And yes the blowback 9mm uppers can be hard on the pins in the lower.

Part of the trigger compatibility issues were with the older bolts that did not have the ramp cut on the bottom. Most new bolts have the ramp cut now.

I used a Colt mag compatible complete dedicated lower from CMMG with their lower parts and haven't had any issues with the trigger or pins. I am using a Fulton Armory 604 upper, Rock River barrel and CMMG bolt. The thing runs like a top. And teh CMMG trigger is actually nice for a GI trigger, it is very easy to do controllable double and triple taps quickly.

One of mine has the 9mm specific hammer. I just stoned and polished it, added JP springs and tapped out the grip screw hole into the receiver so I could install a 1/4-28 set screw to adjust sear engagement. My standard $11 trigger job, gets a pretty decent trigger.

I have another upper I use with endomags on various lowers with regular .223 hammers as well as other custom trigger groups, all seem to work just fine.

berettaprofessor said:

From what I’m reading, I’m concluding it has more to do with whether your bolt is ramped or unramped than the trigger. If you have a ramped bolt, it seems you can use standard triggers. Unramped bolt; you have to use specific 9mm triggers.

that sound about right?

Click to expand...

Correct for the most part. There are some GI full auto hammers along with other types that are not compatible. Most semi-auto triggers made now day will work just fine with the ramped bolt. And stay clear of any drop in trigger unless the manufacturer states wit works with a 9mm blowback upper AND you use anti-walk pins.

The trigger incompatibility is due to the hammer's "height", some match triggers run short so the bolt rides over it but since it's "short" it does not fully reset and when the bolt goes back into battery the hammer follows it home. Usually this just an annoyance but can sometimes cause a discharge.

The most problematic hammer that I recall is the Rock River National Match trigger. The solution is any full sized hammer such as the ALG ACT.

I'm fairly sure this info is ramped bolt specific.

I have substituted the ALG ACT trigger in both of my 9mm dedicated AR receivers. I have a CMMG and a recently purchased PSA both using stick mags. No issues so far...

HJ857 said:

The trigger incompatibility is due to the hammer's "height", some match triggers run short so the bolt rides over it but since it's "short" it does not fully reset and when the bolt goes back into battery the hammer follows it home. Usually this just an annoyance but can sometimes cause a discharge.

The most problematic hammer that I recall is the Rock River National Match trigger. The solution is any full sized hammer such as the ALG ACT.

I'm fairly sure this info is ramped bolt specific.

Click to expand...

Thank you.

I knew there was more to it but I couldn't think of it when I made my earlier posts. Yes part of the compatibility issues is from the height of the hammer. It is basically a tolerance stacking issue between parts that causes problems. Hammers to long or too short along with bolts with or without the ramp cut.