It's true that 21 is sort of arbitrary, and 20 or 22 would be as logical or illogical. I picked it because it is the current law, that's all. If you want it to be 20, I have no problem with that. But it has to be some age, and it ain't gonna be 5 or 6.
Why not? In the earlier half of the last century, there were no laws governing the minimum age for purchase and possession of a firearm. None. My grandfather carried a .22 rifle on his way to and from school, and kept it in the corner of the classroom during school hours, alongside all the other kid's rifles. We're talking about youths aged from 6 to 16.
Unbelievably, despite a complete lack of controls, 8 years olds were't gunning each other down in the streets. Go figure.
I had access to firearms from .22's to hi powered rifles and magnum revolvers from as early on as I can remember. My father never kept them under lock and key. Instead, who chose to instill a set of morals in us kids that were a far more effective deterrent regarding the misuse of weapons than any text in a book of statutes.
Believing that a 6 year old cannot handle a firearm safely and responsibly is buying into the nanny state doctrine. They can, have and do.
I believe in no age restrictions for firearm possession. Eliminating the age requirement is not going to automatically arm the hordes of second graders in this country. Young kids don't buy their own guns. They can't afford them. This means that the parent buys the gun for the kid, and that generally means that the parent is also a shooter and, as such, can teach the juvenile how to safely and responsibly handle a potentially deadly impliment.
As far as teenagers, well, we all know how effective the minimum age of 18/21 has been in keeping pistols out of the hands of 15 year old gangbangers. So why should the good kids have to suffer?
Oh, FYI, since you claim to be a scholar, surely you know already that there is no federal law setting forth a minimum age regarding private party purchase and possession of a long gun. If a six year old can afford a rifle, he can legally buy one from a non-licensee. Of course, some states do have regs, but my point remains.