this of course is nonsense. The only place a bump fire rifle would be more deadly than firing standard semi-auto is in the one in a million situation of the Vegas shooting - where the shooter has an elevated position and is shooting into a large mass of people such that he cant miss, or perhaps shooting into a mass of people sitting in stadium bleachers. Why? Because otherwise you can't hit the broad side of a barn using them. For first responders, someone taking aimed shots, who knows how to shoot a rifle, would be much more deadly.
Looks like we need to ban ALL rifles ...