One flaw that is clearly apparent is that you are not diversifying where you collect your information from. If you get it all from one spot you are going to get with it any imparted bias the collector/author may have intentionally or unintentionally included.
As for the US/Australia comparison, that is comparing two whole separate kettles of fish. For starters, Australia has no international land borders. Have a look at the illegal immigrant rates in the US compared to Australia. That right there alone shows how defendable an all water (physical border) is compared to a land border.
And about your "more guns/least safe developed country" part. If you look at all countries murder rates, then you remove the most restrictive gun control cities in the US from the US statistics, then the US falls to somewhere around the lower 5% of the entire world.
Then look at the ratio to firearms used to stop/intervene on a crime and that statistic double to triples the 30,000 annual gun death which is compiled from about 2/3 being firearm suicides.
But just start by diversifying where you get your info, you may start to see a trend.
