I too have the Rem 700 with the short, threaded barrel. Mighty nice with a suppressor.
For a small, youth gun, the Ruger American is chambered in 300BLK. I think there is a Predator version and I think they are all threaded. Had the Ruger been available when I bought mine, I probably would have bought it. It would be lighter and more compact. You can easily find a Encore in 300BLK if you want a single shot with traditional wood stock and forearm. If you're not going to suppress the 300BLK or use in the AR platform that matches your 223 setup with a simple barrel change, you might be better served by a 30-30, 308 or traditional caliber. Where the 300BLK shines is subsonic, in my opinion. It tosses big, heavy bullets at a slow pace that are easily suppressed. My 2 platforms are an AR which is sighted in at 50 yards and the Rem 700 at 100 yds. Beyond that, the drop is substantial. If I wanted a longer range gun, then I'd use my 308. If I wanted a 100 yd rifle only with easy kick, I'd probably think about things mentioned above like the 30-30.
However, I see where the Ruger American is now in 6.5 Creedmoor... distance and little recoil... hmmmm...
The usage of the automotive term "Chassis" to describe what would otherwise be referred to as a rifle stock tells a lot about how over complicated they are. They look like somebody was forced to take a pile of junk laying around a shop and weld/glue it all together to come up with a makeshift stock.
