I honestly don't get how anyone can believe that a ban on handguns will make handguns more difficult to obtain than how difficult it is to obtain marijuana now (that being not difficult at all.)
For that matter, consider how well Prohibition worked out. History does not bear out an argument that banning handguns would be successful.
US firearm deaths per 100,000: 10.3
UK firearm deaths per 100,000: .25
Italy firearm deaths per 100,000: 1.28
Canada firearm deaths per 100,000: 2.38
Other industrialized nations regulate firearms far more stringently and they have far less gun violence. We have a long way to go culturally and in terms of urban violence, but it's not surprising that regulation actually works when implemented in a smart way.
Key term is "culturally". Or to consider along the lines of what I was talking about before, banning alcohol was an unmitigated disaster while banning lots of other drugs fared better. Firearms restrictions would probably have some effect, but cross-national comparisons are inane when the countries being compared are so different in regards to gun culture.