CMMG .22lr Conversion Kit
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cyphertext
US Veteran
I have a CMMG dedicated upper and it works great. Not sure switching to .22lr is going to help your issue with finding ammo though. 
rojodiablo
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22lr is rarer than BigFoot around here still.
I like the CMMG dedicated uppers more than the conversions; gas tubes wind up getting dirty, and the barrels do wind up holding more lead as the rifling is different, and it's putting more spin on the ammo, which does not seem to toss accuracy, but I have seen more than 1 squib from soft lead bullets which came apart in different spots within the barrel.
That was a little disconcerting; it was ONLY in a 1/7 twist barrel, and with some very soft ammo. I have not seen it in any 1/9 barrels, and most the conversions have been pretty solid performers, so take it with a grain of salt.
I like the CMMG dedicated uppers more than the conversions; gas tubes wind up getting dirty, and the barrels do wind up holding more lead as the rifling is different, and it's putting more spin on the ammo, which does not seem to toss accuracy, but I have seen more than 1 squib from soft lead bullets which came apart in different spots within the barrel.
That was a little disconcerting; it was ONLY in a 1/7 twist barrel, and with some very soft ammo. I have not seen it in any 1/9 barrels, and most the conversions have been pretty solid performers, so take it with a grain of salt.
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I've shot a few hundred rounds with the conversion and no issues other than not cycling correct with a lower FPS rated round.
I HAD one of the CMMG conversion units in an M4gery. Still not sure why, because I cleaned the bore religiously-- but it cost me a barrel--bulged.
I replaced it with a LW barrel which was what I wanted anyway, and for .22 got a 15-22. Should have done that in the first place.
I replaced it with a LW barrel which was what I wanted anyway, and for .22 got a 15-22. Should have done that in the first place.
cyphertext
US Veteran
I'm curious about how a conversion unit would have bulged your barrel. I can see how one was shooting rapidly and did not stop after a squib load, thus ruining the barrel... but that would be operator error and could happen in a 15-22, or a Ruger 10/22, or any other rifle.
Ibmikey
Member
PSA has had some awesome sales on 5.56 ammo lately, with 62gr Federal at $.37. You certainly ought to be able to shoot your M4 for that price. I keep 6-8 thousand .223 and 25-30 thousand rimfire on the shelf at all times so I so not concern myself with the "ammo insanity" that falls every few years. My dedicated DPMS .22 LR is a really fun rifle to shoot with all the weight and look of an M4 (uses 1x16 .22 LR barrel) but the 15-22 seems to eat more ammo and receives more "can I try that" from friends.
CptCurl
SWCA Member
I have both a DPMS dedicated .22LR upper and a CMMG .22LR dedicated upper. Both are fine pieces of machinery and very accurate.
For the reasons stated above, I would not use the CMMG conversion unit in a 5.56mm barrel. The twist is wrong, you will mess up the gas system, and you may lead the barrel resulting in problems with the 5.56.
I first bought the DPMS upper. I use it on an M16A1 lower. To my chagrin I learned that the DPMS upper will not work full-auto. CMMG sells a kit to make its upper shoot full-auto. So I ponied up the money to buy a CMMG upper and the FA kit. It's a hoot on full-auto.
To the OP: Get a dedicated .22LR upper. Don't get the conversion. Good luck!
For the reasons stated above, I would not use the CMMG conversion unit in a 5.56mm barrel. The twist is wrong, you will mess up the gas system, and you may lead the barrel resulting in problems with the 5.56.
I first bought the DPMS upper. I use it on an M16A1 lower. To my chagrin I learned that the DPMS upper will not work full-auto. CMMG sells a kit to make its upper shoot full-auto. So I ponied up the money to buy a CMMG upper and the FA kit. It's a hoot on full-auto.
To the OP: Get a dedicated .22LR upper. Don't get the conversion. Good luck!
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cyphertext
US Veteran
CMMG Barrel Bulge
Yeah, me too. But bulged is bulged.
I posted the affair in great detail on a couple of pretty sharp AR sites but no one could shed any more light on it for me. (A search on M4 Carbine.com would probably pull it up.)The upside was that I had the "opportunity" to learn how to replace the original AR barrel with my first choice and it shot better afterwards to boot. The conversion's accuracy was only so-so anyway, and I was getting tired of clearing stoppages as well.
15-22s are out there at about $400 right now. Finances allowing, I'd sure go that route and be done with it.
BTW I shot my first M-16 about 48 years ago, so I am not exactly unfamiliar with the platform or how to maintain it.
Nice day out--think I'll unlimber the 15-22 and make it an even better day.
Yeah, me too. But bulged is bulged.
I posted the affair in great detail on a couple of pretty sharp AR sites but no one could shed any more light on it for me. (A search on M4 Carbine.com would probably pull it up.)The upside was that I had the "opportunity" to learn how to replace the original AR barrel with my first choice and it shot better afterwards to boot. The conversion's accuracy was only so-so anyway, and I was getting tired of clearing stoppages as well.
15-22s are out there at about $400 right now. Finances allowing, I'd sure go that route and be done with it.
BTW I shot my first M-16 about 48 years ago, so I am not exactly unfamiliar with the platform or how to maintain it.
Nice day out--think I'll unlimber the 15-22 and make it an even better day.
NJM15
Member
I sold 333 rounds of 22's to a friend of mine so his daughter could shoot her 22 mosquito she has had since Christmas I was getting 22 ammo at Dicks regularly since I sold those rounds they haven't had any in about 3 weeks. Well at least I made her happy!
Murdock
Member
The CMMG is the Atchisson design, marketed for years by Ceiner. They are excellent.
I put many thousands of .22LR through my 20-inch Bushy. Federal bulk works well. Just make sure you clean the chamber out well before you start shooting 5.56 again because a dirty chamber will interfere with seating centerfire rounds (Duh!). Rimfire ammo is very dirty. Also, a couple of centerfie rounds through the gun once in a while seems to keep the gas tube clear.
I have since obtained a dedicated CMMG upper, but this is a refinement to improve accuracy (which wasn't bad with the conversion unit; I could always hit a 6-inch steel gong at 70 yards offhand if I did my part) and now I don't have to re-zero the sights when I change calibers.
Go for it.
I put many thousands of .22LR through my 20-inch Bushy. Federal bulk works well. Just make sure you clean the chamber out well before you start shooting 5.56 again because a dirty chamber will interfere with seating centerfire rounds (Duh!). Rimfire ammo is very dirty. Also, a couple of centerfie rounds through the gun once in a while seems to keep the gas tube clear.
I have since obtained a dedicated CMMG upper, but this is a refinement to improve accuracy (which wasn't bad with the conversion unit; I could always hit a 6-inch steel gong at 70 yards offhand if I did my part) and now I don't have to re-zero the sights when I change calibers.
Go for it.
I have a CMMG dedicated upper and it works well with regular .22LR ammo. Accuracy is fine for plinking but it certainly isn't target grade. I also have a CMMG conversion unit that I use in a Colt M4 with a 7" twist. As noted above, that's too fast for normal .22 ammo as the normal twist is 1 in 16". However, there is one load that works well in the conversion unit with a fast-twist barrel and that is the Aquila 60 gr. subsonic load. That bullet is long enough and heavy enough to stabilize well in the 7" twist barrel. In fact, it really doesn't work well at all in slower twists like the old 1 in 12 of the M16A1 or the 1 in 16 of regular .22LR barrels. Accuracy in the faster twist barrels is excellent, penetration is way more than regular .22 ammo and function is at least acceptable if not quite 100%. I know .22 ammo is hard to come by, but if you can find some of the 60 grain stuff try it in the fast twist barrel with the conversion unit. You'll be pleasantly surprised at how well it works.
