So back in Nov. I bought a CMMG 22lr conversion for an AR chambered in 223/556. My barrel is a 556 chambered PSA Freedom 16" mid-length pencil profile in 1:7 twist, so nothing special but a hard one to find. The sight I use on that upper is a Holosun 510C, which is a circle dot reflex site...I'm not sure what size the dot is. The lower is also something I assembled, but I did stick LaRue MBT in it.

So on my last range trip I tried out 5 different types of 22lr at 25yrds and used my range bag as my rest(which works fairly well honestly) off a concrete bench. I shot 5 ten shot groups.

CCI mini mag 1235FPS grouped at just over an inch at about 1.2" grouping.
CCI AR tactical 1200FPS shot like a shot gun at about 2.5" group
Federal Auto Match 1200FPS also shot about like the AR tactical with about a 2.5" group
Aguila Super Extra lead 40gr RN 1130FPS shot about 1.3" group
Aguila Super Extra copper wash 40gr RN 1255FPS shot about 1.1" group, but I had a flyer that opened the group up to 1.9" approx. I'm not sure if it was me or the ammo on that flyer.

I guess what I'm wondering, is that about what I should expect for performance in one of these conversion kits?

Thanks
220

It's not the kit so much as your barrel.  A 7 twist is way faster than typical 22LR barrels and the groove diameter of the barrel is larger than a typical 22LR barrel.  Add the freebore of the 223 chamber adaptor and you have a lot of negatives.  I have a few dedicated 22LR uppers with 16 twist barrels in the correct bore and they all shoot dime sized groups @ 25 yards with decent ammo.

.22LR in a 1/7 barrel isn't going to win any contests.   I use a conversion kit in an upper with a 1/9 barrel and it's noticeably more accurate.

Minute of jackrabbit at 30 yards is pretty much it.  

twist is way to fast its ripping the bullets apart.

My 1/12 A1 upper is easily more accurate with my M261 conversion then with it in a 1/7 twist carbine or my A2. Sure you have watch the cant with a 4x Colt scope on it but it still gives tighter groups.

Yeah, I'm not knocking the conversion kit...I knew it would less than ideal going in. Honestly I'm okay with the groups that were just over an inch with my setup. If I had a magnified optic I'm sure I could have improved, marginally.

I conducted a test using AR-15 22 LR conversion kit in several AR-15’s with different twist.   My experience with 22 LR conversions is to expect fliers regardless of the twist used in 5.56/223 barrels.  The rimfire bullets are .223 and might be copper washed or plain wax coated lead and is commonly shot in 1:16 twist rimfire barrels.   Ammunition can make significant difference in accuracy but fliers are very frequent.   I posted my conversion test on this forum but you can still see my test with pictures of my targets on rimfire central at the link below.


https://www.rimfirecentral.com/threads/ar-15-22-rimfire-conversion-test.754849/#post-7117985

I have a DPMS adaptor that I haven't used in a dozen years. I think I was getting 5" at 25 yards, maybe worse.

Got a old Spikes conversion I'll have to do some accuracy  testing but I'm sure it's not great out of my 1-8 and 1-9 twist Ar..  I do love the o-rings to help keep the chamber clean.

As said, it's about your bore size and barrel twist.  If you want better accuracy, use a dedicated barrel.  If I want better accuracy, which is already good enough to shoot soda cans to 100, I use Aguila SSS (Subsonic Sniper) 60gr rounds.  I never bought an appropriate barrel to shoot the stuff but I realized it's wonderful in a 1:9 twist barrel.  It's also nice they are subsonic for suppressor use.

I used a 'nam vintage barrel with the 1:12 twist and it shoots 22lr pretty well

I'd be happy with those groups.
I tried a friend's conversion kit in my BCM 14.5" lightweight middy 1/7 and CCI mini mags wouldn't group better than 5" at 25 yards.
Went with an RTB dedicated upper and shoots tighter than my Ruger American rimfire.

That was my experiences when using the M261 conversion kit with the M16A1 and M16A2 while I was in the Army. The A1 was always more accurate than the A2 when using the conversion kit due to the slower twist rate.

Stock 10/22 rifles shoot 4-8moa?  I don't own one, but I would have expected a bit better than that.

Well, I do own one and it shoots a hell of a lot better then 4moa.  I put a 2.5x scope on it and it prints tiny clusters @ 25 yards.

That's impressive.  22Plinkster has an old video with a conversion kit and a 5.56 rifle; he didn't do nearly as well.




Think of a 10/22 not so much as a rifle but more a semi assembled kit to make a rifle.

You might get one with a trigger that is rough and heavy, has an action that rock back and forth in the stock, or has a barrel with a loose tenon to receiver fit.  I free floated a stainless Ruger barrel and found that at 25 yards it would start on target cold then walk around in a two inch circle as it warmed up.  I've seen guys with older ones shoot good groups with stock components and decent ammunition, but that doesn't mean you can just pick one up at Cabelas and expect it to shoot an inch or less at 50 yards.

I never had a 10/22 on which I ultimately kept the Ruger barrel.  Getting a new barrel from Rimfire Sports was just too easy and affordable.  Get a better trigger and an OK optic, and nice groups are within reach.