Australia FTW. Seemed to work there.
http://www.gizmodo.com.au/2015/06/australia-hasnt-had-a-mass-shooting-since-1996/
The story of Australia, which had 13 mass shootings in the 18-year period from 1979 to 1996 but none in the succeeding 19 years, is worth examining.
The turning point was the 1996 Port Arthur massacre in Tasmania, in which a gunman killed 35 individuals using semiautomatic weapons.
In the wake of the massacre, the conservative federal government succeeded in implementing tough new gun control laws throughout the country. A large array of weapons were banned – including the Glock semiautomatic handgun used in the Charleston shootings. The government also imposed a mandatory gun buy back that substantially reduced gun possession in Australia.