You're right. I don't get to tell you what to do. However, that's not how laws work. That's not even what freedom is. You can do whatever you want with whoever you want until what you're doing becomes a danger to the rest of society. Why is driving over the speed limit against the law? Because it becomes dangerous to the rest of us. Why is illegal drug use like heroine, cocaine, meth, etc against the law? Because its dangerous to the rest of us.
I have no desire to take away your toys. None. Zip. And I know I couldn't even if I tried. Go take your 3 showers a day. The problem is, your toys are being used to kill lots of people at once. They're not killing as many as hand guns are, but they kill a lot of people in one sitting. Unfortunately, the rest of society is becoming uneasy with these "toys" of yours.
The solution is not for me to mandate how you should manage your stuff. I personally don't think anyone really needs to own an AR-15, but I recognize that the best solution isn't to take them away or ban them. The solution is for YOU to manage your toys. If you want to own and enjoy an AR-15, then you better be willing to subject yourself to self-regulation that ensures that people not like you, you know, the ones going around killing 30+ people at once, don't get their hands on them.
Freedom is the right to govern yourself so that others don't have to. Maybe you should practice it.