Our son was graced with a CO2 operated air rifle when he was nine or ten, can't remember the brand but it was .22 caliber and was a humdinger. He brought back lots of wild Rock pigeons and squirrels from his hunting jaunts and also a pheasant once. What the heck a pheasant was doing running around in a cow pasture in SE Texas I don't know. He moved up to a regular .22 rifle when he was fourteen and got his first deer rifle, at fifteen. I think it was a 6mm Remington, daughter's first deer rifle was a .250 Roberts built on a Mauser frame with a store bought barrel. I built both the deer rifles for them in my gun shop. Alas, after they grew up they've never hunted again and I sold their rifles for them. Seems they liked the money more than the rifles.
I got my first .22 rifle at age 5. A Winchester 1906 pump gun, could use shorts, longs, and long rifles in it. Gave it to son when he went off to college and sure as shooting, someone hit the trailer he was renting and took that rifle and his Remington pump shotgun, not to mention his TV, stereo and even a good bit of his clothing. That .22 was a really nice gun. When I came home from the Navy in 1960 I finally plugged the barrel at the back end, poured it full of mercury, then plugged the muzzle. Let it sit a week and then poured out the mercury and all the lead that had stayed in there for years and years. Sure did shoot better after that.
George