There is something missing from that study, and that is the type of bullet used in each calibre. I am darn sure there would be a difference in fatality rate, regardless of calibre, if they compared FMJ/solid bullets compared with hollow-points or other bullets designed to expand. There is a reason Black Talons by Olin were discontinued. Because they were devastating with their damage to the body.
They were comparing actual shootings in Boston which would have included a wide range of load and determined that had all the heavy caliber hand guns been lighter, it would have implied a 40 percent reduction in fatalities. Interestingly they had just one recorded fatal shooting with an AK47, all the rest being various handguns. Gangs and criminals like small cheap guns. Hollow points are much more expensive than FMJ so it stands to some reason FMJ are most common in crimes. Certainly if limited to lower caliber handguns upgrading ammo would be an effect to consider but their sample size is probably too small to make any reliable determination.
The American insanity: you cannot buy alcohol under the age of 21. to buy weapons you only need to be 18 (in Texas).
I think I found the logic behind these strange rules. They probably want to avoid that anybody younger than 21,but older than 17, would get drunk and kill people with the weapon they could buy as they are over 17. So if you see anybody with a weaopon, being under 21, you are at least sure that person is not drunk. Correction: SHOULD not be drunk... American politicians are really very smart.
This is why this happens in America. Dumbass people go on tv and tell people we need ballistic blankets and trip wires instead of responsible gun laws…
They work all across the world, do they? There's another country out there with even 1/10th the amount of guns in circulation already? And what about your suggestion to give kids in 4th grade firearms. That work around the world, too?