What seems sensible to you may not be sensible to me. What is it you think is sensible? Minimum age of 21 to purchase semi-automatic rifles? I think it's probably unconstitutional but it's that way for handguns so I don't know why it couldn't be the same for rifles. What about shotguns? Minimum age of 21 as well? How about the young adult who wants to go duck hunting? This is where I begin to have a big problem with this kind of restriction. Also, if 21 is to be the new age that people are old enough to be trustworthy, then I suppose that's the minimum age for military service as well. And, the new minimum age to vote.
Or, would you rather ban ALL semi-automatic rifles and shotguns, and confiscate all the ones that already exist?
Or is it the sensible background checks, which already is a law in my state. We can't legally sell a gun without going through a licensed gun dealer, who does the transfer paperwork and the background check on the buyer.
Here's the problem I have with any of these things- it won't solve the issue of people killing other people. It's still going to happen, and a few more restrictions on guns won't make a bit of difference, in my opinion. What's really needed is to have a way to lock up people like Nicolas Cruz, who was posting on social media that he was going to be the next school shooting. People like that- lock them up and throw away the key.