According to a January 12, 2011 Huffington Post article (http://www.huffingtonpost.com/2011/01/12/gun-laws-around-the-world_n_807700.html#s222572&title=Australia_), the country with the most restrictive gun laws is Australia, the country with the least restrictive is Brazil.
According to Wikipedia, (http://en.wikipedia.org/wiki/Gun_violence), Australia, the most restrictive country, has a gun homicide rate of .31 per hundred thousand people, the United States has a gun homicide rate of 3.97 over ten times higher. This was from a U.N. study from the year 2000.
An earlier U.N. study from 1997 (http://www.allcountries.org/gun_deaths_by_country.html) found the gun homicide rate of Australia was .56, the US 6.24 (again, over 10 times greater), and the rate of the country with the least restrictions, Brazil, to be 25.78 (50 times greater than Australia).
The total homicide rates are about equal to the gun homicide rates. This means that people without guns are not finding other means to kill people. People without guns simply kill less than people with guns. The best hypothesis is that the more restrictive the gun laws the fewer homicides.
According to the Center for Disease Control (http://library.med.utah.edu/WebPath/TUTORIAL/GUNS/GUNSTAT.html) In the U.S. for 2006, there were 30,896 deaths from firearms, distributed as follows by mode of death: Suicide 16,883; Homicide 12,791; Accident 642; Legal Intervention 360; Undetermined 220.
It is reasonable to assume that if gun control laws were as restrictive as Australia’s, gun homicides would drop to the same level as Australia’s rate, about 1/10th of the present level. We would expect the 12,791 deaths to drop to about 1,279 deaths. That would save about 11,000 lives a years.
People are justifiably upset that 6,000 Americans have been killed over the last 9 years in the wars in Iraq and Afghanistan. A calm and thoughtful foreign policy would have saved those 6,000 American lives (not to mention over 1,000,000 Iraq and Afghan lives). However, strong gun control measures would have saved over 100,000 American lives during this same period of time.