We have three children, ages 14, 13, and 9. Here’s what I’ve done, and it works well for us. We’ve never had any problems. YMMV.
All guns in the house are unloaded. No exceptions.
No guns are hidden.
No guns are locked up.
Ammo is often within easy reach.
If there’s an “uninvited guest,” I load a weapon with a mag.
Even though this works for us, I do not suggest it for others. In order for this to “work”, you need to raise children around firearms and get them shooting at an early age. In our household, guns hold no mystery; they are as ubiquitous as furniture.
If most practice is conducted using the. 22lr, one can afford to become proficient with just about anything. The core group of skills remains the same regardless of the gun’s caliber and those skills can be developed and maintained with a. 22lr. If you are skilled with the. 22 then the larger calibers can be picked up quickly. If you are burning center fire ammo just learning basic skills, then I imagine lots of cartridges, most of them in fact, are too expensive to learn to shoot well.
Final thought: dry fire, except for the initial cost of a snap cap, is free.