That is regrettably the short form, the one everyone uses for either for support or to point at. Lacking the specifics your question makes total sense. But the answer is easy... you don't make a shovel when you can buy one, and people in other countries do go on shooting sprees, like that Breivik fellow. One shooting spree versus maybe two a year here, but we outnumber Norway 60:1, hence one incident in thirty years equates to two a year here.... except we haven't had two or three a year, we've had less than one a year, 20 in 30 years, a frequency of 1 per 1.5 years or 1 per 50 year per 10 million people. Sweden, population about 10 million, had one 18 years ago, thus has a higher rate of spree killing than the US, France, population a quarter of ours, has had 3 in the last 20 years, the equivalent of the US having 18 spree killing in 30 years, 90% of ours. The UK had 5 in about 25 years. The Netherlands had one last year. Many countries we have no data on, or unreliable data, but what we can see of US-parallel culture and wealth with gun controls laws is no significant increase or decrease in spree killings. Since the Uiryeong massacre of 1982, 57 dead in S. Korea by a disgruntled cop (kinda hard to keep weapons from them) you've had 20 shooting sprees in the US, and 18 in Belgium, Finland, France, Germany, Netherlands, Norway, Sweden, and the United Kingdom... same time, nearly the same population, not sure who has more total there. People play games with the data, both sides, you can cherry pick total deaths or by weapon or etc and have gun laws helping or show the opposite, but the data seems to come up as roughly even. Craziness occurs everywhere and black markets or legal stores make it easier to acquire than home manufacture. Same as LSD or meth, you can make them, easier to buy them, but if you really want one, you will get one.