Santa the only one I ever beat the crap out of was the one who accidentily shot me. And that was more because I was pissed than he shot me than over the safety issue. Not the right reason, but it felt good to let it all out. And to his credit, he dinnae fight back, so I dinnae whoop him too bad. I think he beat himself up enough, partially because the next day he returned that particular firearm.
All the others just get a good, solid, open-handed squeak-slap. I find that will drive home the most important points faster than all the talking the world. Especially when they've made the same mistake twice and were told about it the first time. Guns aren't toys. I learned the hard way, and when I made the same mistake twice I got slapped hard for it. I learned the proper respect for firearms early on, and back when it wasn't illegal to actually punish/discipline your kids (but that's a whole different, though related, story).