Depends on the constitution, I am not arguing that you don't have a point, I too believe that the measures we take should always be in relation to the case we're talking about. But if I take Germany as example, there is nothing in our constitution that says that weapons have to be a right - and I would argue, they are perceived by the public in Germany more as a privilige anyway. No clue how it is with the rest of Europe, but I am not aware that there would be many constitutions that explicitly mention that weapons can't be banned. Albeit, I think most people would feel very uneasy with that thought. I definetly would, as I feel that banning weapons completely because of mass shootings or crimes etc. is pretty much the most stupid thing a state could do. It would have a similar appeal, like banning video games completely to protect children or for some other silly reason, even though it doesn't solve the problem in the slightest. FOr some reason, you will have always certain groups that target some medium or object for like ALL of the problems, rape comes from porn, violence from video games (in the 90s it was TV ...), and of course mass shootings come from weapons or video games or weapons in video games, or video games in weapons ... you get the picture.
But I am very glad that we have in Germany and I think most of Europe a very responsible and level headed gun culture and most of our weapon-fanatics seem to be more on the reasonable side of the spectrum. I don't know ANY weapon owner who would feel comfortable with 5 or 6 year olds shooting automatic weapons, or any weapon at all, on a gun range, be it with or without supervision. This, kidz-with-weapons should be really the bare minimum that any weapon owner should accept as a problem in my opinion.
With saying this, I also believe that we shouldn't forget that we're talking about a hobby here. The thing is, I would even enjoy owning a weapon and shooting it on a range. And one of the weapons I would love to own would be a G3 or Fn Fal, but I understand that owning fully automatic rifles is simply not possible in Germany, and that for very good reasons in my opinion. But you can own bolt action rifles and certain rifles for the civilian market, I think like the HK8 a civilian version of the G36.