Sure. Why Not?

 "At the risk of opening up a can of worms, how about as a single issue how about raising the age for AR-15's to 21?"

Congress has been under a lot of pressure lately to "Do something!".  This is something that might evoke bi-partisan agreement, which is what they need nowadays to get anything passed.  I doubt it will make a noticeable dent in the mass shooting numbers, but at least they will be able to say that they did something.  I think a guy has to be over 21 to buy a handgun in Michigan already.  

Remember handguns?  There was a time when they were the primary target of the anti-gun crowd, but you hardly ever hear them mentioned anymore.  I hear that Canada is currently cracking down on handguns, but I thought they were already banned in Canada.  The reason I say that is I met a guy in Alaska back in '63 who said he was not allowed to carry his handgun through Canada when he crossed it to get to Alaska from the Lower 48.  What he did was ship it to himself and then reclaim it when he got there.  When I drove through Canada on my way back from Alaska, they asked me at the border if I had any handguns and I told them no, only a shotgun.  They asked me how much ammunition I had for it, and they had no problem with the modest amount I was carrying.  If I had over a certain amount, I forget how much, they would have put it a sealed container which I would have been forbidden to open until I crossed back into the U.S.