I know little about the AR 15 platform and 15-22. I am looking at aftermarket drop in triggers. Do these units such as CMC for example (I looking around online) require any modification to function in the 15-22? Are the springs suitable for the 15-22 and get reliable ignition or are their modifications that have to be made to the drop in trigger units to function properly in the 15-22?

The short answer is yes, you can swap out the trigger group for an aftermarket one. There are multiple threads on the subject that cover it more in depth as to what works and doesn't work best and what they have used.

Pretty much any AR15 trigger will work, from 'binary fire' to any cassette or drop in style. CMC are well known upgrades for the 15-22 for a while the slidefire kit for the 15-22 came with a CMC trigger.

Lots of peeps on here have tried different drop in triggers and as far as I am aware, there have been NO compatibility issues, regarding light strikes or the like.

For what it is worth I put a 24C trigger in for reliability with primer strikes and have not had one FTF since. It is a really nice FCG and the added bonus of no light strikes I would (and have) recommend one to anyone who asks. That being said there are plenty of triggers equally as good.

From a $11 spring job on your factory trigger, up to a $300+ FCG the world is your oyster...good luck deciding

Some are better than others regarding light strikes on the little rimfire. I currently have the Hiperfire 24C and really enjoy the innovative technology and flat trigger. Believe the lightest pull on mine is advertised at 2lbs though mine registers 1.5lbs using two different gauges. Some folks like them a bit heavier for assorted reasons. Mine has zero pre-travel and reset is approximately 1-1.5mm. Some manufacturers recommend using anti-rotation pins, some advise against it, some don't say either way. Timney recommends using their thin metal shim beneath the trigger assembly cassette to prevent their set screws from digging into the polymer receiver. If you do get the anti-rotation pins, get the ones specific to the 15-22 and not for an AR. The 15-22 pins are slightly longer. Many folks keep it in the "mil-spec" family and go with the ALG ACT assembly or the Palmetto State Armory EPT assembly. ALG Defense Combat Trigger-ACT-Tuned By Geissele PSA is currently out of stock but can be purchased many times during the year on sale for 30.00 ALG Defense Combat Trigger-ACT-Tuned By Geissele

I also like the 3lb. Timney Competition in one of my ARs. I've seen only a couple of reports of a light strike with this one in a .22lr. It comes in either 3lb or 4lb / slightly curved or flat trigger. Timney AR-15 Trigger Assembly 3lb Solid Trigger

All very useful. I can see trigger selection can be a hobby into itself :-)

The key line in Bamashooter's response, IMNSHO, is this:
If you do get the anti-rotation pins, get the ones specific to the 15-22 and not for an AR. The 15-22 pins are slightly longer

Many (most? all?) drop-in triggers provide pins that may be too short for the 15-22, or provide pins specifically for the 15-22. For most of the drop in triggers, I believe you can use anti-rotation pins - if you get a set, get one SPECIFICALLY for the 15-22.

Drop in triggers are any trigger and hammer combination where you do not need to mess with the springs - they are internally encased and allow you to 'drop in' the entire group.

Non-drop in triggers (such as the standard hammer/trigger that comes with the 15-22) require a bit more finesse to align the holes for the trigger and hammer.

There have been many reviews of different triggers, and one (perhaps) surprising outcome has been that drop-in triggers tend to have less pre-travel, break crisper, and have less over-travel than their non-drop in counterparts.

Having said that, I run ALG (non-drop in) triggers, CMC drop in triggers, and geiselle non-drop in triggers in my various platforms.

I just put the 3.5 lb JP hammer and trigger springs in my MP15-22 so far,bout 400rds,no issues sofar,fact trigger was 5.5 lbs

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I hav tried the Geissele SDE and the hyperfire Eclipse (similar to 24C). Both are marketed as single stage triggers. Be advised that both of these triggers have significant pretravel and are very different from your typical single stage. Not unlike a glock or double action revolver trigger. There is about 3/16” of pull at the full 2.5 to 3 lbs before they break. Both seem to have very comparable performance. I have run at least 2000 rounds through each with virtually no light strikes or failures to fires. However I wouldn’t necessarily classify them as having a crisp break in the classic sense due to the long heavy pull. These may be good for action shooting where a quick reset is more important than precision shooting.

Edit- I have the geissele SD3G not the SDE noted above.

I'm surprised the Eclipse has any pre-travel. Like my 24C, it's marketed with having none which my 24C has; none.

Geisseles' SD-E is a two stage trigger:

"Full Description

The Geissele Super Dynamic-Enhanced (SD-E) Trigger featuring an exclusive flat trigger bow, is a finely-tuned two stage trigger providing enhanced trigger control and weapon accuracy while maintaining the robustness and reliability of our combat-proven two-stage trigger."
Super Dynamic Enhanced (SD-E) Trigger

My 24C has a glass rod type of break...could not be more defined or crisp. I would have thought the ECL being made of 'better' material would have been the same if not 'better'? Add to that Tomcatt51's comments on the Geissele....has me wondering...

I’m sorry my bad. I have the geissele SD3G. It is marketed as a single stage. I stand by my description of it and the hyper fire eclipse. They both have a very similar feel with about 3/16” of heavy pre travel before they break. They are unlike any typical single or two stage triggers and more like a glock or double action revolver trigger pull.

I have the SD-3G in my 15-22s for Rimfire Challenge. It's a single stage meant for speed events. Definitely not your usual single stage break but it's not meant to be. I've "adjusted" the hammer notch angle in the Volquartsen Scorpion I use for the pistol part of Rimfire Challenge to have the same type break as the SD-3G.

Agreed!


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The ECLipse would be going back. Per ECLipse "Virtually No Take-Up", that's just what they mean.

Here is a quote from WC Armory re: Velocity drop-in triggers:

"No claim of compatibility with the following rifles.
No AR-15 22LR AR type rifles (see the 4# steel case ammo trigger for this compatibility)
No AR-15 9mm conversion or any open bolt face
IF YOU HAVE A POLYMER LOWER, we recommend putting a Velocity stainless steel shim underneath the trigger to protect the polymer lower. Please click here to order your stainless steel shim for this purpose."

Anti-walk,anti-roll pins come with the trigger at no additional cost. But the method Velocity uses to install the trigger I wonder if anything other than replacing the factory pins is needed. The Velocity uses set screws to push the trigger housing up against the hammer pin and trigger pin to secure the trigger housing. The holes in the housing are intentionally large and pins will drop out until the trigger housing is snugged up against the pins through the set screw system. I may be wrong on this but this is the best I can determine. I plan on calling the Velocity manufacturer tomorrow. Does anyone here use the Velocity drop-in trigger? Apparently WC Armory advises against the Velocity triggers other than the #4 Steel is for harder strikes and reliable ignition.

I was using a Velocity 4lb trigger and it was ok. I would have occasional lite strikes with it. I have since move on to a POF 3.5lb trigger with the straight bow and very happy with it. They are about the same price as the Velocity when they are on sale.