I tried the Cmmg .22lr conversion kit in my M&P 15 and had numerous cycling failures using CCI mini mag copper plated round nose. Same failures with bulk ammo. Jamming occurred consistently after one to three rounds. Needless to say, it's being returned.

I read numerous positive reviews about this kit and don't plan on buying another. Did anyone else have this problem?

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Inconsistently consistent

No.
Mine is fantastic. So sorry to hear of your difficulties: I'd hope a replacement might run better. Best of luck.

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Now go make God proud...

Mine works flawlessly. I keep the AR quite clean when using it, as .22 lr is a notoriously dirty round and tends to foul up the works on some guns... Try a thorough cleaning of the rifle before doing much else. I use CCI standard velocity with good results.

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NRA Endowment Member

Mine also runs flawlessly. I run it in a dedicated upper and get great accuracy with Aguila Super Extra 40gr.

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213th FBINA

Mine does pretty darn good, hard to tell from the pictures but what magazine are you using?

I've had both the CMMG dedicated upper and currently am using their conversion unit with no problems.

I have used both CMMG magazines and S&W M&P 15-22 magazines in both my upper and conversion unit without any problems to speak of.

I have completely polished my conversion unit, paying special attention to the bolt guide rails and feed ramp in an effort to eliminate any break-in period which may well have helped.

Mine works like a charm. Runs perfectly.
Looks like you may be having some extractor issues. Check it over carefully.

I'm using the cmmg magazine that came with the kit.

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Inconsistently consistent

The extractor looks good, no chips and the spring is operable. The feed ramp is not smooth, which may be part of the problem.

One other thing, the magazine has a lot of back and forth sloppy play, about an inch of travel measured at the base.

I don't want to mess with the ramp since I'm expecting a return authorization.

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Inconsistently consistent

Personally I'd go ahead and return it, then I'd try a different one.

Too many positive experience replies to give up without trying another IMO.

I also added a plug in the buffer tube because I detected rearward movement of the unit, although it was working fine before I added that part anyway.



ETA: Just checked magazine play measuring at the lowest tip, it's 3/8".

Some may find that this little shim comes in handy when utilizing their CMMG kit with .22 mags:
S&W 15-22 Magazine Adapter (Clip on)



– AR Catch22

It’s what I use and it really seems to help. There is one you can stick on the mags, but I didn’t want to go that route since I use in several different style AR lowers.

I've used the Better-Mag .22 S&W adapter in a Sig M-400 and currently in my Ruger AR-556.

I really like the S&W magazines for ease of loading and the adapter feature that makes use of the rifles actual bolt stop.

Better-Mag S&W(R) .22 Rimfire Magazine Adaptor - Redi-Mag

After reading Smithpride's post, I made a thin wedge from plastic that took up the back and forth play. It was more like 3/8" .

After sending three glorious cci 40 gr cprn's downrange, same old malfunction. It seems that the extracted casing is hitting a cartridge that is stuck or slowed on the feed ramp.

I'm definitely buying another. The odds of getting another lemon are high. Thanks all for the replies.

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Inconsistently consistent

CMMG customer service got back with me about the malfunctions. I had since purchased a CMMG charging handle that has a solid underside that was supposed to eliminate the stovepiping. Same results with malfunctioning.

I told them that their 22 lr conversion worked flawlessly with Chiappa magazines. Then they sent me two CMMG magazines to try, a 22ARC and a Mk4/AR15.

The 22ARC worked flawlessly. No malfunctions with the 22 lr conversion. The other (Mk4/AR15) did the same as the original Bravo kit magazine as they are the same design. It caused a jam/stovepipe with each round fired.

I requested that I keep the 22ARC magazine and send back the two Mk4/AR15 magazines.

I'm happy now.

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Inconsistently consistent

To my surprise, CMMG Customer service rep, Bryan, sent me two 22ARC magazines free of charge. These are an older style magazines that works with my 2013 Sport.

I've been shooting my 22 conversion frequently for almost a month without a malfunction.

CMMG has a new, repeat, faithful customer.

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Inconsistently consistent

Thank you for the update, and nice work seeing this through to a satisfying conclusion.

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Now go make God proud...

I have a CMMG dedicated 22 upper. I actually special ordered the whole rifle from them. Multi caliber lower with the 22 upper.

Few years ago my firing pin broke into 3 pieces. Sent CMMG a email with pictures. Around a week later I received 2 new firing pins.