CMMG .22 conversion
 

I ordered a .22 conversion for my soon to arrive spoon. This is a very slick looking piece or hardware. It drops right in, and you are good to go with .22LR in a mater of seconds.

I can't wait to try it all out...

http://cmmginc.secure-mall.com/shop/images/1264.jpg

http://cmmginc.secure-mall.com/shop/.../1481-2102.jpg

My concern with the drop-in kits is how do they prevent a .22LR case from partially lodging in the barrel? It seems to me the only thing preventing this in this design is the extractors. In other words, a broken extractor could mean a case stuck way up in the chamber. The shoulder and back end on a standard .223 cartridge would prevent this.

Also, will the charging handle fit over that bolt?

The .22LR seats in the 'kit' there is no way for it to get lodged in the barrel.

Yes, the charging handle fits over the bolt and functions as normal. It just travels less.

The only thing that doesn't function is the bolt release. (I think that's what it's called. It holds the bolt back after your last shot of the mag.)

Looking at it again, the extractor doesn't hold the case at all once it's seated. It opens and closes at it slides.

I have one. Works great. The conversion completely fills the .223 chamber, no chance for a .22 case to get jammed in there as far as I can tell.

The only draw back is the barrel twist rate which is way off for a 22 rimfire (1:8 vs 1:12). It is for the 5.56/.223 bullet and the several I have seen at the range in Delzura CA really scatter their bullets. For plinking the drop in can not be beat and you can make a 550 round box of bulk ammo go a looooooong way compared to the bigger stuff!

One of these is in my future too.

I have a stainless version. Everyone who's shot with it loves it. With rim fire you get more than a few FTFire, but who cares when the brick cost the same or less than a 20 rd box of 5.56.

The .22 rd is surprisingly accurate despite the twist rate.

Chris, the front of the .22 adapter is shaped like a .223 case and sits in the chamber. The .22 round has its own chamber behind that. There is a slide within the adapter that gets blown back againsts a smaller spring. The slide holds the extractor and is charged with the standard charging handle. The AR buffer and spring sits idle the whole time.

If one were inclined to build a .22 pistol with an AR, the buffer tube, buffer, spring and stock can be ditched. A cap can be screwed into the rear of the receiver.

I got the stainless as well.

I hope I don't wish I'd gotten the 16" 1/9 twist instead of the 18" 1/7 barrel. I really wasn't thinking I'd get the .22 conversion when I ordered the AR.

You'll be fine. If you end up disliking the 18" 1/7 twist, I have a 16" CMMG 1/8 barrel I would trade you and give extras :). Just send me your upper, and I'll swap it out and send it back. The upper is not considered a firearm so non FFL required.

I have watched this video 3 times - looks real fun!

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by far the best ar accesory bang for buck...

Coolest g-damn movie music of all time!

I shot an AR15 with the CMMG conversion a few months ago and it was great! The owner said it's pretty accurate out to 50 yards, but then accuracy drops off quickly. I'll be ordering one ASAP...

What is the difference in diameter between .223 and .22LR?

None

According to wikipedia the .22LR has a bullet diameter of .223 in (5.7 mm) and the .223 Remington has a bullet diameter of .224 in (5.7 mm). So if this is correct it's only .001"

That's what I thought.

So a .223 caliber/5.56 mm rifle has lands that are .223 and grooves that are .224.

So a .223 diameter .22LR bullets will not be forced into the grooves like a .224 diameter bullet.

Then the accuracy decrease past 50 yards makes sense.