Same here.When my son was younger he wouldn't have even thought about touching a gun without me being there.He's well taught and has proven that he could be trusted so he gets a key.I actually have more faith in his gun handling abilities than I do most adults,so as long as my wife is home,he can grab a gun and shoot whenever he wants.I have a rifle range right out the kitchen window with spinner and gongs and a place to set up a wheely bird trap that can be seen from the house.He's not aloud to touch a gun if another kid is around though.The penalties are harsh in my house so most rules aren't broken.Actually,I can't remember the last time he touched a gun without at least calling me at work to see if it was Ok.Trust has to be earned and it's easily lost.He's earned it.Both of my kids got pretty long leashes growing up but I'm a miserable sob if they screw up and they fully understand how miserable I can be.
Sounds like reasonable, responsible parenting to me. It allows for rewards for doing right and consequences for not doing right.
When you are up to your butt in alligators, it is hard to remember your intent was to drain the swamp. Stay focused!