Not to mention that many of those dedicated AR .22 can be a little cranky in operation. I have seen a few of them puke in rimfire competition.If I was just going to use it for some AR practice it is a legitimate option. If I was planning on shooting tactical matches with it, I prefer the AR15-22 as it is stone reliable. The difference is comparing something designed from the ground up to be a .22 and oh, yeah you can use lots of AR parts to something that was only made into a .22 as an afterthought, and costs as much as a .223.