I understand what you are saying Bunnys but so-called assault-style rifles aren't full auto military style rifles (which are banned). They are semi-auto just like most pistols are. And as I pointed out in several other posts, those pistols, as well as a standard 6 shot revolver, can be easily fired continuously and for hundreds of rounds if a shooter just changes out clips (magazines) on a pistol, or uses speed loaders in the case of a revolver. A person can carry as many pre-loaded magazines or speed loaders on their person as they want since they are so small. They can also carry several loaded handguns on them (like Adam Lanza did - just like all mass shooters have) and just grab a new one (or 2 or 3 or...) once they are out of ammo. Same with a .12 gauge shotgun (holds 9 rounds of ammo that can kill several people in one shot if close) or a standard hunting rifle that can hold 15 rounds. Both can be fired repeatedly very fast even though they are not semi-automatics (although there are a lot of semi-automatic hunting rifles and shotguns out there that will not be included in this ban). Both can be made much smaller and easily concealable. And while they are not easily reloadable like a pistol or revolver is, a mass shooter can carry several of them at once - as most if not all mass shooters have done. So banning one type of firearm or type of magazine won't eliminate mass shootings because most - all - can be done just as easily with firearms and magazines that won't be part of the ban. So unless you completely ban all firearms including hunting rifles and shotguns- really anything that can fire more than one round before needing to be re-loaded by hand - a ban a one firearm won't matter or make a difference. That is why addressing the intial cause of these kinds of shootings is so much more important then spending all that time and effort to get one type of firearm banned. That does nothing to address the problem or the cause.
As far as the response time issue - well if it takes less than a minute or two to gun down several people and it takes the police 5 or 10 minutes to respond after they get the first call, then waiting for the police to arrive on scene may mean many many more could die.