I believe the idea is that banning certain types of guns with large capacities and rapid fire, that the carnage at mass shootings may be less. For example, if the Las Vegas shooter didn't have an array of high capacity semi-autos, he may have killed 10 folks and wounded 25, rather than killed 50 and wounded 500.
So the idea isn't to "solve" the problem of crazies with guns, but rather limit their ability to cause multiple deaths in a short period of time.
I'm not saying I support these types of bans; I'm merely describing what appears to be the motivation behind them.
The problem with that is that there are many
millions of these weapons currently owned by Americans, and 99.999% of them will never be used to harm innocent life. They are, however, highly useful in defending and saving human lives.
Bear in mind also that these are not automatic weapons, they are not "weapons of war", nor do they allow the truly high rates of fire associated with such military weapons. If outfitted with so-called "bump-stocks", an AR-15
can fire more rapidly by reducing the time required between trigger pulls, although with a significant sacrifice in accuracy (which of course, did not help those poor people in Las Vegas).
But that sick, twisted bastard never should have had access to a gun in the first place, and that is primarily a failure of law enforcement, FBI background reporting and the detritus of cultural rot.