And that's correct---the murder rate in the United States dropped more on a percentage basis, after the Australian assault weapon ban + confiscation, than it did IN AUSTRALIA. So what does THAT tell you?
That if you skew a consideration hard enough you can almost make data say anything you want.
What you can't do is undermine the objective data field we have across multiple countries and comparative data between states. I've set that out with links more than once. The fact remains that every country with strong, universal gun laws does a marked better job at keeping their citizens safer from gun violence and mass shootings. Equally true, the stricter state laws correlate with marked lower rates of gun violence and mass shootings. Will there be outliers in nearly any statistical examination? Sure. But the rule is pretty dramatically supported.
On rate declines, Australia had a fairly low homicide rate at the time of the Port Arthur massacre that gave birth to tougher gun laws. In 1996 the homicide rate was 1.6 per 100k. We were at 7.4 per 100k at that point and falling, a thing I'll take on more particularly in a moment.
Australia's rate of overall homicide was about the same during the buy back of 1997 as it had been for them in 1996, because it was low to begin with and mass shootings, horrible as they were, didn't make up much of that figure. Anyway, low as it was, by 2014 it had dropped to 1 per 100k, or approaching a reduction approaching half of what it was before the laws. What the tighter gun laws were mostly successful in doing (the rate being fairly low and gun laws prior not being comparably lax as, say, Alabama today) was to make mass shootings much harder to come by, which was the point of the Port Arthur related laws. In the 18 years prior to that incident Australia had witnessed 13 mass shootings. In the 22 years since those laws there have been none.
Meanwhile, in the U.S. we had seen, with the rise of the enormous baby-boom population, an unprecedented rise in homicide rates. As the 60s closed we averaged 7.3 murders per 100k. The rise continued until most of the 70s saw nearly double digit deaths nationally, per 100k. By 1980 the number reached that double digit figure.
From 1972, when we hit 9.0 per 100, until 1994, when the beginning of the aging of those baby-boomer began to impact the numbers to the good, in those 23 years our murder rate was 9 or better 14 times. It was 8 to 8.8 seven times. Or, it dipped below 8 only twice during that stretch.
The decrease in rate that began in 95 continued to follow that generation's decline steadily. From 96 to 97 it declined by .6, to 6.8. The following year it declined .5 to 6.3. By 2000 the rate was back into the 5s, and by 2010 we were back into the 4s, in the high norm for 50s to mid 60s.
To compare murder rate drops by percentage between Australia and the U.S. is to mislead people unless you set out those numbers.
Meanwhile, between 1997 and present date, since the imposition of laws taking the weapons most successful in mass shootings out of easy access and commercial circulation, there have been 0 mass shootings in Australia.
In the U.S. where those laws are not in place, we've had 168 so far this year, with 235 dead and another 597 wounded.
Here are the death tolls in the U.S. from mass shootings since 2013 on the left, with a / plus the number of dead and then the same numbers in Australia each of those years. You can figure out the comparative rates if you like:
2013: 339/ 467 dead. Australia: 0/0 dead.
2014: 325/ 364 dead. Australia: 0/0 dead.
2015: 371/ 469 dead. Australia: 0/0 dead.
2016: 477/ 606 dead. Australia: 0/0 dead.
2017: 427/ 590 dead. Australia: 0/0 dead.
That's what the laws were gunning for in a relatively peaceful country otherwise. Looks fairly effective.
I don't have the numbers for us prior on hand so I borrowed this limited data set from Mass Shooting tracker, which uses the FBI definition and notes and links to reports of each incident in every year since they began to accumulate the data. So far, with Australia giving us 16 free years, the comparative toll is:
U.S. 2,107 mass shootings, with 2,731 dead. Australia: no mass shootings (though one near, by definition) and no fatalities. I have a feeling that if we add the other years it looks even worse for us. Just a hunch, mind you.