Australian gun laws would not be acceptable in America. In the USA the NRA fights having fully automatic machine guns and pistol silencers restricted.
I believe machine guns, assault weapons, silencers, and say magazines of more then 10 rounds should be banned. Current magazines available I know of hold up to 100 rounds.
The 2nd amendment was created when single shot muskets were in use and not machine guns. I believe in the right of citizens to own guns but not guns that have been designed to kill people. Gun reform is not removal of the 2nd amendment.