My father prohibited BB guns !! This based on the observation that all too many kids and all too many adults thought they were toys. I agree with him !
Reactive targets are a great challenge. I used to put the empty 6 or 7 oz frozen juice cans out in the field .When hit they bounce , changing position to something that's more , or less visible.
When more expert use animal crackers as targets ! This BTW is challenging for adults at a 50' indoor range.