AR-15 .22 conversion report and ??

[TDDude]

I bought a CMMG .22 conversion kit and man, is it fun to shoot.

At 30 yards and under, I just put the red dot on the target(s) and go to town. It's a whole lot of fun shooting at a row of coke cans and other trash that's lined up on a berm.

However, at 50 yards the accuracy really suffers and I was wondering if anyone out there has better luck and if so, what .22 ammo are you using. I was using the $16/550 round brick that Acadamy sells. This ammo shoots very well in my bolt action .22 rifles but the AR don't like 'em.

[mr surveyor]

I'd bet you're going to have to uprade your ammo choice a bit...maybe at a minimum try some CCI Stingers, if you want a bit more range and accuracy.

[dcphoto]

Or perhaps some CCI Mini-Mags. My bolt gun and 10/22 seem to like those the best.

Edit: Actually, my bolt gun will shoot just about anything well, but that's beside the point.

[NcongruNt]

The problem you're likely running into is the transition from supersonic to subsonic speeds. In general, most high-velocity .22LR ammo will have this problem at around 60 yards, so any shots after that distance are going to suffer from the effects of turbulence from the transition.

The real way around this is to use subsonic ammo. There is a reason match .22LR is subsonic - it doesn't ever transition. The only other option if you're shooitng at 50-100y is to get a hold of some of the Aguila SuperMaximum ammo, which pushes the bullet out at something like 1750fps, which is sufficient to keep a .22LR round at supersonic velocity out to 100y. I have a box of this stuff I bought at Cabela's, and have been quite happy with it.

[TDDude]

The problem you're likely running into is the transition from supersonic to subsonic speeds. In general, most high-velocity .22LR ammo will have this problem at around 60 yards, so any shots after that distance are going to suffer from the effects of turbulence from the transition.

The real way around this is to use subsonic ammo. There is a reason match .22LR is subsonic - it doesn't ever transition. The only other option if you're shooitng at 50-100y is to get a hold of some of the Aguila SuperMaximum ammo, which pushes the bullet out at something like 1750fps, which is sufficient to keep a .22LR round at supersonic velocity out to 100y. I have a box of this stuff I bought at Cabela's, and have been quite happy with it.

The barrel's rate-of-twist plays a big role, too - a slower twist (1-in-15 or 1-in-16) is better-suited towards those stubby little bullets, rather than the faster 1-in-9 (or so) found in typical .223s barrels these days. A .22 bullet tends to be over-stabilized in those, leading to key-holing and the groups opening dramatically at the longer distances.

If you really want accuracy, you might want to look into a complete .22LR upper.

Ah-HAH!! I knew someone would have an answer. Both scenarios I hadn’t thought of.

I can go with the subsonic or the SuperMaximum. I’m not interested in getting a complete .22 upper.

Anyway, now I know and thank you so much.

[MoJo]

The barrel's rate-of-twist plays a big role, too - a slower twist (1-in-15 or 1-in-16) is better-suited towards those stubby little bullets, rather than the faster 1-in-9 (or so) found in typical .223s barrels these days. A .22 bullet tends to be over-stabilized in those, leading to key-holing and the groups opening dramatically at the longer distances.

If you really want accuracy, you might want to look into a complete .22LR upper.

[Chuck TX]

Yep, never going to get great accuracy with a conversion kit vs. a dedicated upper. The 1/7 or 1/9 twist rate just won't be as friendly as a 1/16 to the light grained .22LR. Same concept as the 1/7 twist AR being better at stabilizing heavier bullets like 77gr while the 1/9 twist better suited (than the 1/7) to deal with lighter bullets like 40gr and so on.

For the same reason a 1/9 twist AR with a conversion might be a little more consistent than a 1/7 twist AR with a conversion kit.

[retrieverman]

My brother talked me into buying a CMMG conversion, and I could be happier. In my opinion, for what it is, the accuracy is great. If I want match grade accuracy, I will buy a match grade 22 rifle.

My brother spends alot of time on AR15.com, and those guys swear the cheap Federal bulk pack is the best ammo for the CMMG conversion for both accuracy and function. I have put a couple hundred rounds through mine without a hiccup.

[texasag93]

The only problem I have is when I use brass washed .22 that has a slight tarnish.

When I leave a brick of 22 in my tool box, it tarnishes after a week or 4.

Other than that, I have never had a problem. I prefer the brass washed as I go through several hundred rounds and my fingers are not black from the lead.

I loved my CMMG so much, I bought a spare to let other people try.

The 27 round mags are very good. I have not tried the 10 round.

At 50 yards, I can tear the center out of the bulls eye even with rapid fire. At 100 yard, I can hit a man sized target consistently, but not with great accuracy.

texasag