Set up a little shooting range in your basement! Airsoft guns are perfect for indoor target shooting and much safer than pellet guns for that purpose. Most out-of-the-box airsoft guns shoot under 2 joules (about 460fps with a .2g 6mm BB) so your backstop can be as simple as a cardboard box filled with more cardboard. At 25ft with a decent airsoft gun you can hit a quarter-inch to half-inch target every time.
Most pellet guns shoot over 2 joules (about 300fps with a 7.5 grain .177 pellet) and they go WAY up from there so they get out of toy territory pretty quick.
The only challenge is convincing your wife that shooting BB guns in your basement is acceptable behaviour for an adult!