Guns aren't designed for mass shootings or murders.
Which guns are you talking about? Because in some cases you may be right, in some you are definitely wrong. One thing is for sure, all guns were designed to damage people/places/things. Many of them are designed to kill large numbers of humans, like the machine gun. It’s irresponsible to pretend that they won’t be used inappropriately a non-zero amount of time.
Machine guns were designed for covering fire, not necessarily for mowing down large groups of people. Sure, they were sorta used that way when trench warfare was popular, but modern combat doesn't allow for that. And really, the purpose of an inanimate object is irrelevant to the topic when comparing deaths. For sake of argument, lets assume that guns are designed for killing, that still means more people die accidentally from vehicles than purposely by firearms. Also, you're equating warfare with crime. I stated that no firearm was designed for mass shootings and murder and here you are saying that they were used for mowing people down in war time. Guns are designed to shoot projectiles at it's intended target. They may be made to be more suitable for self defense, hunting, target practicing, or combat conditions, but none were designed for mass shootings and murder.
Even cars, which are absolutely not designed to hurt, kill or maim, are legislated to protect people against their misuse, or reckless use to some degree.
It's the same with firearms. You think it's legal to go on a killing spree, shoot up the neighbor's house, fire indiscriminately into the air, or brandish a firearm in a threatening manner? Firearms have the most regulations aside from the tax code.
And some of the these controls make a fuck ton of sense in the gun arena, like ensuring that people get licenses so they know what they are doing, prohibit people who are not sound of mind and body from using them. Really basic stuff.
It's not common sense if there's no statistics to back it up. States like Illinois and New York have stringent training requirements in order to carry and they don't seem to have a dramatic effect on negligent discharges compared to states like Vermont which you don't even need a permit to carry.
Since your constitution loves guns and war, people have a right to arm themselves so you would have to make this process with very few barriers to entry, but your society proves time and again that it is not healthy or mature enough to handle the responsibility of guns.
If we didn't have guns, You would be saying the same thing about our knifing and clubbing rates. In fact, in the UK, knife attacks are on the rise.