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Posted: 7/21/2005 9:24:33 PM EDT
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I have a couple of spare uppers and I was thinking of building a dedicated .22LR AR upper. I have a criner kit for my 1911 and I love it! I use all the time. So what do I need to know for this build? I have a M261 conversion unit, what else do I need? What twist rate is best? 1/9? 1/12? Do I have to worry about any sort of head spacing? TIA! Matt |
| If you need a barrel for the rimfire build anyway you should buy a rimfire barrel. Even slower twist and smaller bore dimension. Chamber it for the ammo you will use. There are differences in rimfire ammo. A tight chamber is accuracy enhancing with match ammo but too small for stingers..... |
| Most .22 LR are 1:16 twist. I have a DPMS .22LR upper and it functions great. Accuracy is not on a par with my match built 10-22s and only 10 round mags are available but the rifle is a hell of a lot of fun and holds between 1.5 to two inch groups at 50 yards with ammo that my 10-22s will hold into an inch or less. Despite its free-floated 1" bull barrel it is not what I would call a match rifle, but is certainly will put the hurt on squirrels under 50 yards. |
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On the right is the .22 I built my son: M261 coversion kit J&T Light Weight barrel 1/9 Colt Upper Oly Lower At 25m it groups about 1" which is fine for my son to practice his basic marksmanship skills. When he's ready for 5.56mm then we will buy a bolt and carrier. When we do make the swap to 5.56mm the entire gas system will need to be cleaned, after about 500 rounds the gas tube is allready plugged with lead. 
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