i was given my first revolver at age 12.....a single action ruger .22 by my grandfather who knew i was capable of handling it responsibly (certainly times were different back then, but in rural north carolina where i grew up it was acceptable during that era). i inherited my first 1911 at 15 from that same grandfather. oddly enough, my older brother didnt get his first .22 rifle until he was 17 because he didnt demonstrate the maturity and responsibility to be trusted with one before then. my point is that its impossible to determine the right age because people mature differently. being old enough to join the military doesnt automatically make you mature enough to be responsible.
being old enough to join the military means nothing....actually joining on the other hand, and successfully completing basic/ait is a demonstration of both capability and maturity. i say if youve joined the military and completed basic/ait that you should be allowed to both drink and own handguns. if you havent, wait until 21.
i know that no plan is perfect and i myself can find fault in it......what if you simply dont trust the current administration under which you would serve, etc? since no plan can be perfect you gotta draw the line somewhere and this one seems about as reasonable as ive ever heard.