A blanket ban will (a) have a miserable compliance rate, (b) dramatically increase the value of firearms, and (c) help ensure that law-abiding citizens are defenseless against criminals (who generally don't care if they're already breaking the law).
In the 1990s, California attempted mandatory registration of "assault rifles." Compliance was about 10 percent, and was officially acknowledged a failure.
I can't imagine what a total ban would look like. House to house patrols? With whom, the army? I'm guessing that nobody would want that job. I conjecture it'd be unconstitutional, or appear that way to enough soldiers and policemen that they wouldn't enforce it.
There are 300+ million guns in private hands in the US, in 50M+ households. This is a "wicked problem" if you're looking at a gun ban as the solution. Estimates I've read put the time to effectively zero guns in private hands in the 200-250 year range. A ban just isn't going to be pleasant; it might result in /worse/ violence, both immediately (in reactions and protest) and over time (through creation of victims) -- of course this is not testable, so it'll have to remain rhetoric.
I'm going to guess that arming lots of citizens isn't the answer, either. States with concealed carry permits /appear/ to be safer than those without, but a rational deterrent is not going to stop someone who's irrational.
In an ideal world we don't need guns, and everybody has a pony. We don't live in an ideal world.
tl;dl; Firearms bans in the US are really really hard.