AR-15 .22 LR conversion

[RugerFan]

I picked up a CMMG .22 LR conversion and tried it out in one of my AR-15s (1:9 twist). I cleaned the rifle after about 60 rounds fired and was surprised to find a fair amount of leading. I had never fired cast in this gun before, so the leading was definitely from the .22 LRs. Anyone else run into this?

[CastingFool]

When I was in the Air Guard, sometimes we were issued M-16's with the 22rf kits. No one liked them, as they didn't shoot accurately at all. Had to keep the mags covered, away from the sun, as the heat made them expand, creating feeding problems. As far as leading, we only got to shoot the rifles. Someone else had to do the cleaning at the end of the day.

[xacex]

I have a M261 that I use. No problems with rem G/B's. Definitely not as accurate as 5.56 or 223 in the same gun, but still fun to use, and good to have.

[wlc]

I've got a dedicated upper based on the M261 kit. Proper bore/twist etc. Probably have a thousand rounds through it and haven't noticed any leading. IIRC 22rf is a different bore size than 223/5.56. That could be the problem.

[clodhopper]

Bore diameter on 5.56/.223 is .224
bullet diameter on .22 rf is .221-.222
Some guy says thier conversion kits shoot ok, and if it's good enough for them who am I to argue?

[RugerFan]

A Ruger 10-22 has a 1:16 twist so a much faster 1:9 is probably part of the problem. With some Googling I see that some folks recommend only shooting the plated .22 LR rounds and not the bare lead ones (I was shooting the later). Now I know.

[xacex]

Winchester make's a plated bullet just for the 22 conversion kits. I think they are the M-22's with the black (tactical) coating. I don't shoot uncoated lead .22's in mine.

[Doc Highwall]

I bought a Spikes dedicated upper that has a Lothar Walther match barrel and it shoots great out to 300 yards. Another problem with the 22 conversion is the first 1.5" approximately has no rifling right at the chamber and gets a running start before hitting the rifling with a barrel that has a 224" groove diameter, great for 25 yard blasting.