This singular event was quickly used as a rationale for the banning of most firearms for Australian civilians, but the new regulations were not a product of Port Arthur.  Rather, anti-gun politicians had been pushing for restrictions and confiscation for many years prior; Port Arthur simply gave them enough public panic to get their legislation passed.

This is the modus operandi of the typical anti-gun lobby – Wait for a tragedy and then exploit it to punish all law abiding citizens for the crimes of a handful of deranged people.  It doesn't make much sense unless you realize that gun control laws are not meant to thwart criminals, they are meant to thwart good people who might object to government trespasses.