I don't get the fascination with semiautomatic rifles. By FAR, the vast majority of murders are done with handguns... Why so much focus on rifles that make up less than 4% of the yearly gun deaths? Based on statistics, the primary focus should be dealing with the suicides that make up around 2/3 of gun deaths...
Always be suspicious of anything written by Philip Alpers, a known gun control advocate. He will intentionally and subtly move definitions where it suits his narrative. For example, his claim that there have been no mass shootings in Australia since 1996 is false unless you use an incredibly restrictive definition of a mass shooting.
This analysis is also confined to mass shootings, an incredibly rare event outside of USA. Statistical analysis of very rare events using restrictive definitions to exclude results should be treated with caution.
"Two buyback programs and 26 uncompensated amnesties between 1996 and 2015 resulted in the surrender of 1 038 089 **illicit** firearms (2)."
Most of the guns handed back in the buybacks had been legal up till that point. You do need to actually follow through the links to find that the underlying data perhaps doesn't support at least some of the assertions.