I totally agree, but it's fun to confront these guys with those facts to see how they try to explain away the facts. They usually use the "slippery slope fallacy" argument when the facts are presented to them.
Ban semiauto rifles, and then handguns would become favored. The argument is "at least they aren't as high-powered as a rifle!". Then they'd want those banned because of their high capacity, so then revolvers would be used. Even though fewer people would be killed with a revolver, the argument would be, "One life lost is too many!", and then revolvers would be banned.
Criminals would still have access to all those guns anyway, but that would be ignored. After all, we have to do "something!"