Anybody set up an AR22 built with a CMMG conversion specifically to shoot the CCI SemiAuto Quiet ammo? If so, what recoil spring did you use that would cock the hammer and lock back after the last round? The one I want to build will use Better-Mag parts and S&W M&P-15 .22 magazines and Blackdog S&W drums.

Updates below.

I would assume it would just run right out of the box. Haven't tried it to be honest. I have some though soay have to give it a whirl.

It will not run on the 710fps CCI quiets.  You would need to remove some weight from the bolt by milling, probably around 1 oz total.

OP is referring to Quiet SA.

Specifically designed to cycle semi-autos.

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Unless you're locked in, because you bought a ton, it's not really worth it. It's costlier than std and, with a decent suppressor, equally as quiet. Port pop and action noise will be louder than the report.

Standard Velocity is louder than Quiet Semi-Auto.

Not on my ar22 with dedicated suppressor. As I said, the only thing you hear is a little port pop and the action cycling. I've got a delrin bump, delrin adapter, lubed spring with o-ring, and ball detent mod.

At first, I thought so too. But then, I wondered if CCI engineers even considered AR22s when prototyping the SA. The hammer and disconnector springs on a standard g.i. trigger set are pretty tough. Rifles like the 10/22 or the Glenfield 60 were probably utmost in their minds.

I suppose there are the softer after-market recoil springs like the BoreBuddy ones, and trigger/hammer kits like the JP and Kaw Valley, which might address the problem if it rears its ugly head.

Thanks for your reply and please re-visit this post if you give this ammo a try. At this point, I'm still in the planning stage and would like to have to replace as few parts in the final assemblage as possible.

I'm familiar with the two Delrin parts, but what are the o-ring and ball detent mods?

One simple mod you can do the the stock hammer spring that I do on every mil-spec hammer is to bend one leg about 45 degrees starting about 1/4" past the coil.  This not only helps reduce pull weight but it allows the hammer to begin cocking with less energy spent.  I have not had any reduction in reliability as yet, there is sufficient spring rate left to get the hammer moving when tripped.

Good post. I've heard of others doing this as well with similar results.

O-ring goes between spring and carrier. Bolt "snorkel" hits it instead of carrier.
Ball detent mod is floating around somewhere. There's usually a hole in the bolt, where you drop a spring and BB. You put cuts in the carrier, where the BB fits, to add a manual delay. It helps a lot with  FA, but benefits SA too.

Scroll down for "Ball-detent mod" how to:
http://bazookabrothers.com/pages/technical+assistance/3

Thank you both. Very informative.

FYI, my 4.5 inch CMMG with standard hammer and trigger with JP “yellow” reduced power springs will eject and feed, but not cock the hammer, with CCI subsonic segmented “Quiet” ammo.  This same ammo will not eject or feed in the Ruger 10-22 Takedown with standard hammer, trigger, and springs.

I have not tried the bent spring mod on the AR-22 yet but since it is so close to working, I have some hope.  I feel confident that the CCI Quiet semi-auto ammo, if it will work in the 10-22, will do just fine in the AR-22, at least with JP reduced power yellow springs.

I just tried the JP Yellow reduced power hammer spring, bent and 30* and then at 45*, and it made no difference.  With the CCI Quiet Segmented ammo, it would fire, eject, and feed, but not cock the hammer.  I guess I'll have to wait and see how the Quiet Semi-Auto ammo does.

I may try it tonight...I will have to setup a range in my garage.

Received the rest of the parts I needed and did some experimenting today. Below is what I ended up using and, so far, it is working perfectly.

Generic AR15 upper and lower receivers
4" dedicated .22LR barrel
CMMG .22LR dedicated bolt assembly
Better-Mag mag-well adapter for S&W M&P .22 magazines
PSA EPT trigger assembly with Kaw Valley spring set
BoreBuddy parts: 3lb.(blue) or 4lb.(yellow) recoil spring, recoil buffer, extractor and spring, buffer pressure plug, crescent firing pin with std. CMMG return spring, Quiet collar

Set up first with CMMG recoil spring, PSA standard trigger/hammer springs, BoreBuddy firing pin spring(lite) This combination would fire most of the time, but would not cock the hammer or lock back. Replaced these parts with the ones listed above and everything works perfectly. It still will not work with either of the 710fps versions of the Quiet ammo, but I did not expect it to or care. As soon as I get another chance to shoot, I'm going to try the BB 4lb.(yellow) recoil spring. If my pistol won't work with a standard recoil spring using the SA Quiet ammo, consistently, I will have to relegate it to this ammo exclusively. Subsonic or standard velocity ammo would work, but they might be hard on the moving parts.

I had to use the CMMG firing pin return spring because I would get occasional failures to fire with the BoreBuddy spring. Evidently, the BB spring is too strong for the KV hammer spring to overcome consistently.

Any thoughts?

Got back to the range today with the yellow BoreBuddy recoil spring installed. The thing worked as perfectly as it did with the blue spring. I think I'm done.

This guy's 15/22 runs CCI Quiet Semi Auto, so theres some hope for an AR22: