Re: 5 year old given rifle as gift, kills 2 year old sister
The US has seen its murder rate drop in half after almost all the states approved concealed carry and the number of guns per capita went way up, so obviously guns aren't the driving factor in homicide. In all of Russia there are fewer privately owned rifles and pistols than just my own city, yet their murder rate is about four times higher than the US. Europe's murder rate is overall about two to four times lower, but European firearm laws vary more than the US states' laws do. Some European countries allow teenage open carry, some ban guns almost entirely. They just don't seem to kill each other as much. US states show similar patterns. Some states are highly restrictive and have a low murder rate, and some allow pretty much anything and have a low murder rate. Some are highly restrictive and high very high murder rates, and some have high murder rates while not restricting guns hardly at all.
Some time ago I ran across a review of gun control/violent crime studies. The authors looked at all of the studies they could find in the US and worldwide that tried to correlate the prevalence of guns with violence and/or murder. The studies varied widely in their conclusions, and what the authors of the paper concluded is basically what you said. There's little to no correlation between gun ownership and the prevalence of violent acts in a society.
Computers are like the God of the Old Testament: lots of rules and no mercy.