What is the purpose of plunking down $1000 for an AR in .22LR? Don't get me wrong, I have some nice .22 cal rifles in semi automatic that are fun to shoot so I guess if you have the bucks it would be something to have for sure. In need of enlightenment.
For training or practice without the cost of .223.
A dedicated upper will have the proper twist barrel so it will most likely be more accurate that the drop-in kits.