The oldest is 7 and he is going to get into the junior riffle program at my gun club this fall when he becomes 8. The others are three and one.
I was instructed on gun safety when I was in boy scouts in the 80’s and the lessons have stuck with me for thirty years.
The real problem is they are all into everything. Even the one year old has the ability to get into high cupboards as he has watched his stealthy twin brothers do so his whole life. I have actually caught the one year old on the counter foot on the first shelf going up. Leaving a gun in a high place is out of the question. A lock box is the only alternative.
Yeah I had every thing on prison lock down for years, sounds like you are in the same boat for the foreseeable future. Good luck.