I am unable to comment DIRECTLY about guns. Instead, let me talk about knives....
I started using a butter knife in my mom's ktchen at the age of 4. Butter. Peanutbutter. Jelly. Mayonaise. I was allowed to use a butter knife to spread those things around on my bread and crackers.
I was not permitted to start handling a REAL kitchen knife until around the age of 5, and only then it had to be for something as mundane as cutting an apple, and I had to be supervised. When my mom served steak or pork chops, my older sibblings all got to have a real steak knife at their place settings, but my food was all cut up for me. I was allowed to set the table EXCEPT I was not allowed to set the steak knives down. I set down all the forks and spoons and butter knives, but the placement on the table of steak knives was forbidden of me.
When I was 6 I was finally allowed to have a real steak knife at the table for cutting my own steak. (I ocassionally got yelled at for making the whole table shake with my inexpert sawing motion.
) I was also suddenly allowed to set the whole table, and then I was also allowed to clear the whole table. I was taught to walk with a knife in a safe way, walking from the table to the sink with a dirty knife so the blade (not the handle) was in my hand -- that way if I fell I wouldn't stab myself or stab someone else--worst that could happen would be I'd slice my palm. That was a very sobering reality I was taught when it was explained to me that it was "preferable" to slice my hand. That was the very first REAL instance of a "lesser of two evils" kind of tradeoff I was ever schooled in. The gravity of stabbing myself or stabbing someone else was driven home to me when I was taught --and when I fully agreed-- that it was indeed far preferable for an accident to result in the slicing of my palm rather than in the stabbing of myself or someone else. That was one of those moments in life when I grasped onto a true measure of maturity --at the tender age of 6! Lots of little measures of maturity would get delivered to me in small increments over the years, but THAT one was one of the most serioius, I think as well as one of the earliest, and one of the most seminal in my traning to become a responsible person with a mind that always leaned toward prioritizing safety above everything else. (And I want to point out that was always a real crybaby as a kid when it came to cuts and boo-boos and running in tears to mommy for a bandaid. So I most certainly did NOT want to slice my own palm! So you better believe I was darned careful about how I carried a knife through the kitchen! And i never did have an accident with one.
At the age of 7 I was allowed to help with dinner by slicing vegetables and cutting meat.
By the time I was 10 I was very adept with how to handle a knife in the kitchen.
So ... it comes down to a matter of degree. Slow, baby steps of cautiously introducing your kid to the realities AND SAFETY REQUIREMENTS of guns in incremental degrees. ::ETA::
Here's a podcast from 18 months ago where Jack interveiwed Chef Maribel, a professioanl chef and cooking instructor who holds cooking workshops for chidlren. During those workshops, she teaches the kids how to use real knives in the kitchen. http://www.thesurvivalpodcast.com/episode-702-chef-maribel-the-food-diva