My dad never locked weapons away - though did keep ammo and firearms separate. He hadn't shown me where everything was until I was a teenager, but by then he had made crystal clear the nature of firearm safety and proper handling.
Is that enough? In my eyes, yes. Someone who is fucked up is going to find things they can use one way or another, and with dedication, it isn't exactly all that difficult. I don't know any firearm salesman that operate out of vans or alleys, but I guarantee it wouldn't be difficult to find one (especially here in Toledo), as long as I talked to the right individuals, probably getting in contact with a friend of a friend of a friend.
And hell, I knew where most of all my dad's things were before I was even a teenager, I reckon. Christmas snooping sometimes ends up with finding things you didn't expect, and sometimes things you wish you hadn't seen. D:
Anyhow, point was made earlier in this post.
Those firearms I've still never touched unless my dad has brought them out. Playing around with guns is an absolutely stupid idea, that was something I knew my whole life. Hell, simply being 8 or 10 or whatever, and hearing on the news some kid your age died when he and his brother were playing around with a handgun they found... that kind of perks up your mind a little. I got the chances to fire those very pistols, or my grandpas rifle, when I was young... out in the country on relative's farm, and felt that was sufficient for my curiosity at that age.
And imho, having weapons locked is simply an excuse to not instill the fear and respect (of firearms) into young children. And such safety measures only add unnecessary delay if one desperately needs said firearms (unless, of course... one doesn't believe in using a firearm inside the house to protect the property... then that delay doesn't ever come into question I guess).