http://en.wikipedia.org/wiki/Dunblane_Massacre
"successful in pressing Parliament, and the then-current Conservative government into introducing a ban on all cartridge ammunition handguns with the exception of .22 calibre single-shot weapons"
"Following the 1997 General Election, the Labour government of Tony Blair introduced the Firearms (Amendment) (No. 2) Act 1997, banning the remaining .22 cartridge handguns, and leaving only muzzle-loading and historic handguns legal, as well as certain sporting handguns (e.g. "Long-Arms") that fall outside the Home Office Definition of a "Handgun" due to their dimensions"
Britain = massacre free since 1996
US ?