If you intend target shooting and/or hunting only, then theres nothing wrong, since you have had safety training. The issue is that even trained, at 16 you should have adult supervision. And if your caretakers arn't willing to do that, leaving you without an adult supervisor...well it's kind of a douchbag move, but they have the right to not want to be around guns.
I count myself as a Liberal. I believe in gun control, and think that the second amendment is both horribly misconstrued and outdated. I also started shooting when I was still in the single digits, age wise. I also remember how safe it was, because when I was 6, I had a toy rifle with no action whatsoever, and I got yelled at for pointing it at people, and making, "Pew pew" noises. Fact of the matter is that if you're shooting at a range because you like to target shoot, you're in a safer pastime then football. I think its time to start calling your mom and boyfriend out on hypocrisy. Do they drink? Smoke? Play sports? Don't check the Carbon Monoxide detector every week? Tell them that they make you feel uncomfortable. You can probably stretch this pretty far, since target shooting at a range is quite safe, and most any behavior is dangerous if you approach it in the wrong way. Make sure that they know that your intent is to remove the gun for use only when taking it to the range, and your not getting the gun for nebulous things like home defense.