A) It's fucking Wikipedia.Deaths from Massacres in the 12 years before Port Arthur Massacre in Australia: 79
At which point Australia, an island of essentially homogeneous population, enacts the strictest firearms controls in the developed world.
Deaths from Massacres in the 12 years after Port Arthur Massacre in Australia: 120
B) I count 46 deaths from 'massacres' in that list in the 12 years after Port Arthur. You were only wrong by about fucking triple the actual number.
That list includes arson attacks, domestic murders and gang violence. Not the type of random mass killings these gun laws are meant to prevent. The number of people who died in an attack comparable to Port Arthur - the mass killing of people unknown to the attacker - in the 12 years after it is 2 according to the ever-reliable Wikipedia. The number of people, not including Port Arthur itself (and it makes no sense not to include it), who died in the 12 years before it was 43.
Falsehoods and stupidity.