There are a couple of case studies in what happens after you ban guns, England being one of the antis favorites to compare to us. The problem with that is that England's firearms homicide rate went
up along with their violent crime rate in general following their ban.
We've also had whole cities turned into "gun free zones" right here in the states for decades and I think we've all seen the effectiveness of that.
We don't have to speculate on the effectiveness of various gun control schemes, pretty much all of them have been tried in one place or another over the years. The CDC even did a study (
http://www.cdc.gov/mmwr/preview/mmwrhtml/rr5214a2.htm) on these schemes which came to the following conclusion:
During 2000--2002, the Task Force on Community Preventive Services (the Task Force), an independent nonfederal task force, conducted a systematic review of scientific evidence regarding the effectiveness of firearms laws in preventing violence, including violent crimes, suicide, and unintentional injury. The following laws were evaluated: bans on specified firearms or ammunition, restrictions on firearm acquisition, waiting periods for firearm acquisition, firearm registration and licensing of firearm owners, "shall issue" concealed weapon carry laws, child access prevention laws, zero tolerance laws for firearms in schools, and combinations of firearms laws. The Task Force found insufficient evidence to determine the effectiveness of any of the firearms laws or combinations of laws reviewed on violent outcomes. (Note that insufficient evidence to determine effectiveness should not be interpreted as evidence of ineffectiveness.) This report briefly describes how the reviews were conducted, summarizes the Task Force findings, and provides information regarding needs for future research.
The CDC is hardly the NRA or the SAF, some might even call them anti-gun. Yet they were unable to find any benefit from any gun control scheme.
Of course the antis will scream that the experiment wasn't closed, i.e. guns were brought in from elsewhere, but when in real life do you ever get a closed experiment? I'd wager that even inside North Korea there's some smuggling going on. Inside the brutal German occupation of Poland people designed and
built functioning submachine guns (
http://en.wikipedia.org/wiki/Błyskawica_submachine_gun).
The English put out a review of the illegal firearms market in their country in 2006 (
http://www.ligali.org/pdf/home_office_gun_crime_the_market_in_and_use_of_illegal_firearms.pdf), the one issue with it that the authors were quick to acknowledge was that it relied on the data gleaned from 80 arrested convicts [users], not on the data gleaned from arresting an illegal dealer [supplier]. Out of the 80 convicts, 6 were in possession of
automatics.
In the end the task of the anti-gunner is to shut down a black market, but when in history has that ever been successfully accomplished? Prostitution, The War on Drugs, Prohibition, pirated software, bootleg DVDs? Guns have been banned in Mexico for how long, yet the criminals there seem to have no problem getting ahold of everything from frag grenades to M203s to real M16s.
But hey, there just might be an anti-gun argument out there I haven't seen yet. But in just my not quite 2 years of gun ownership I've read everything from wanting to ban:
handguns
"assault weapons"
"sniper rifles"
"plastic guns"
all NFA items (they don't think the current laws on suppressors, SBRs, and DDs are enough, they want a total ban)
"armor piercing ammo", i.e. all centerfire rifle rounds
lead ammo
anything .50 cal (but not just .50 cal, in one article they talk about .338 and even .308)
conceal carry permits
open carry
Oh, they also want extra regulation on air guns.
If you'd like I could link you to the relevant articles on the VPC's site where they lay out exactly what they want.