The premise that guns cause murder is easily disproved by looking at guns per 100k and gun related deaths.
France, Greece, Germany, and Australia have gun related deaths averaged at 3.01, 1.24, 1.64, & 0.86 respectively. The U.S. meanwhile has an average of 10.64. When you look at guns owned by country you see France with 31.2, Greece 22.5 Germany 30.3, and Australia at 15. The U.S. sits at 88.8. So those all line up right. Not directly proportional but seemingly so. Then you see Mexico right next to Australia at 15 for guns owned and yet their death by guns is 11.17, higher than the U.S. Surely an outlier. But then you look at Switzerland with 45.7 guns and 2.91 gun deaths and you see a high gun ownership with low homicide rates. Or the opposite of Mexico. France, with the same gun ownership rates as Norway and Sweden, has double the gun death rate of those two. So no, you can't directly link guns to high gun death rates and the attempt to only look at Australia and only look at gun deaths in Australia verses the U.S. is a setup, cherry picked country, but doesn't even pass the briefest of investigations.