I have never seen a kid thats old enough to deer hunt that couldn't handle a .243. If the pop bothers them get ear plugs and if the recoil bothers them get a slip on limbsaver. I won't take a kid deer hunting with anything less than a .243 but I also hate loosing deer. It usually really bothers a kid if they can't find the first deer they shoot. You might let them shoot the 223 some and let them get used to it then step up to the .243 before you take them deer hunting.