Remember that last time I said I was building my last rifle, well I lied! My 8 year old deer hunted last year with my AR in 223. AR's work great for kids because they are short and adjustable. I have killed plenty of deer with a 223 (nothing big mostly during our doe only season) but I view it more as a expert round than a starter round. So I went looking for a replacement. My kid is a little skinny (kind of like his old man) so I have to keep the recoil to a minimum. I think I have found a pretty good match = works in the AR platform, light recoil, double the bullet weight of the 223. Muzzle velocity of 2350 fps with 1350 ft-lb of energy. Almost gets you to 30-30 performance. Just built a new upper so I can use my existing lower. Goofy looking little round but on 100 yard max deer I think it will be a good one.