2nd Amendment to the Constitution of The United States of America

A well regulated militia, being necessary to the security of a free state, the right of the people to keep and bear arms, shall not be infringed.

"I ask sir, what is the militia? It is the whole people except for a few politicians."
- George Mason (father of the Bill of Rights and The Virginia Declaration of Rights)

Thursday, September 16, 2010

CMMG .22 conversion kit for the AR....cheap fun!

Alright, who has an AR? Alright, who shoots it a lot because .223/5.56 ammo is so darn cheap these days?....Yeah, me neither. I take the AR to the range on occasion to verify my zero or for a couple of boxes of ammo to have some fun, but putting serious round counts through it can be a costly affair. Even the cheap Russian rounds will end up costing you in the end. Luckily, the folks at CMMG (who also make all types of AR components) already considered this problems and came up with a nifty solution. The standard .223/5.56 barrel will shoot .22LR rounds, so why not come up with an adapter for the AR that fires them. Brilliant!

This unit has been out for a while and there are plenty of technical reviews on it so I will just give an overall impression of the device. First off, I found the basic parkerized unit (stainless is available) without mags for $99 at Botach.com and got two 26 round mags for about $17 a piece, total cost was about $144 shipped. Unit seemed pretty well made so I slapped some lube on it shoved it in place of the regular bolt on my M&P15 and headed to the range.

Well, the initial results and my impressions were not good! The were numerous FTF/FTE issues in the two mags I ran through it and the mags themselves had to be forced in and out of the weapon. Oh no, money wasted! Well, not quite. I was in such a rush to get it to the range that I did not fully read the instructions (total finger pointing at myself here). After I got home I read them. DOH!! Right on the magazines there had been a piece of paper (that I ripped off) that showed that there were some plastic "bumps" on the back that may need to be sanded down to fit individual weapons. Odd, as the STANAG standard for the AR mag has been around forever, but I guess you got to keep the oddballs in mind too. It also said that the unit would break in over the first couple of hundred rounds. DOH!! AGAIN!! I put about 50 through.

With this knowledge I renewed my quest to get .22's downrange consistently with my AR. I dremmeled off the tabs on the back of the magazines. "Detail stripped" the bolt group (not in the instructions but not hard to figure out either) and gave everything a good coat of lubricant and headed to another range. This time she ran like a champ!! Taking the tabs off of the mags (which are a solid piece of polymer) solved the feeding issues and after 250+ rounds downrange we (Kev and I) only had ONE FTE!! Upon cleaning the rifle afterward I found small bits of metal shavings in the lower of my AR from where the unit obviously "broke itself in" by use.

Now my impression is "MY GOD THIS IS FUN!!" The adapter works pretty much as advertised and its a hoot to shoot. The Rounds were dropping low but that was probably because the sights were zeroed at 50 meters with 5.56 ammo. I wasn't going to change the Magpul BUIS unit just for these but may start using the carrying handle sights that came on the carbine just for .22 fun. I didn't put my EOTech XPS on it just because I wanted to keep the rifle light and fun to shoot.

Next step, going to take it to Appleseed and use part of the day to see how it does on accuracy there.
The CMMG unit (front) next to the regular bolt group for my AR, notice the case shaped extension that goes into the chamber. Since the unit is designed for both .223 and 5.56 rifles, I believe the round will "jump" a small gap from the end of this to the barrel rifling in 5.56 rifles, as .223 is a bit shorter in chamber length.

Receiver halves "shotgunned" with the normal bolt still in the weapon and the adapter ready to be inserted. This, along with the mags, is the only modification that needs to be done to shoot .22lr in your rifle.

I found a handy way to store the unit was in an old AR cleaning kit pouch (from back before the Otis units were all the issued rage in the service).

The unit "detailed stripped". There are no instructions for this, so you just need to figure it out. Give you a hint, spread the bars of the bottom unit just a bit and the front part with the chamber adapter can be slid out and the rest comes off. Don't blame me if you mess up your unit doing this though.

The plastic .22 mags (left), a Magpul Polymer PMAG (center) and a US GI aluminum mag (right). The prevalence of plastic and polymer mags is so wide spread that I thought it best to mark the .22 mags with a purple stripe to mark them as "toy" mags...just in case.

The one FTE we had in 250+ rounds, a classic stovepipe.

The unit does not fully work to make the AR function as it would normally. The bolt hold open doesn't work and even though the bolt "locks back" after the last round it just stops against the magazine follower and will slam home as soon as you remove the magazine. You need to manually pull the charging handle back (which it only goes about 3/4 of the way back as normal with the unit installed) to load each mag. So if you are looking for a realistic training devise to shoot live ammo with cheaper that full power rounds this is not the kit for you if practicing high speed mag changes and the like are critical.

However, as a option to turn your SHTF rifle into a weekend plinker for half the cost of most .22 rifles appeals to you, this will certainly fill that role!!



greg said...

Great review, you convinced me to give one a try. Always been a little skeptical of the accuracy. But wanted something reasonable to practice my high power/service rifle shooting with. My other option and ideally the best would be to go with a Compass Lake but I'm simple not a good enough shooter to justify the $1000+ price tag.

Thanks for taking the time to write it up.

Huey said...

thanks for commenting and I am glad I could be of service..

as an update I should point out I have discovered that the kit is sensative to ammo types...Cheap round nose seem to be the most reliable while HP rounds are somewhat touchy...CCI OK...Blazer not so OK...just buy a brick of lead or fmj and you should be fine..

Christopher said...

I purchased one of these kits after a recommendation from a friend for my M&P-15OR. I took mine to the range and it was horrible at first. Everything you mentioned, exactly as you described. I performed the same tasks as you before I read your review, and since, I have had no issues at all. Thanks for the review. Let's hope others read of our "simple fix" and decide to buy these inexpensive kits for use in their rifles.

-ABF2(AW) Christopher Garrett

Huey said...

Thanks for the reply Christopher..I was just talking to someone the other day how I need to get out and shoot this more!

I take it by the ABF2(AW) that you're in the Navy, thanks for your continued service to our nation. I could never figure out Navy rank though and the entire concept of the khaki community and such. I used to get DD214's from BUPERS for guys that joined the guard after the Navy and could hardly figure them out sometimes :-)