The AR-15 22 LR I built used an upper I got from Kurt’s Kustom Firearms.
The barrel I got from Kurt is a 1:16 twist rimfire barrel with a unique barrel extension. The barrel extension in a solid round opening large enough to insert the 22 conversion chamber insert.
A standard AR-15 bolt will not fit into the barrel extension so there is no possibility of accidently chambering a centerfire cartridge.
This upper uses a Houge round hand guard and the barrel is black CMV with 1/2-28 thread an A-2 flash hider.
I used a four rail gas block on the barrel. I put a sling loop on the non ejection port side and a Brownell’s branded front BUIS.
I assembled a seperate RRA lower to use with the KKF dedicated upper.
As before I used a RRA NM lower parts kit and six position RRA commerical butt stock.
In the previous upper and this AR-15 I’m using Spectre CQB three point sling.