Actually, I believe that there is a better case for civilian ownership of tanks, ordinance, and heavy/automatic weaponry than there is for handguns. According to a study by the US Bureau of Justice Statistics, 86% of gun crimes involved a handgun, even though there are roughly equal numbers of rifles, handguns, and shotguns in the US.

Meanwhile, there's a tanker militia not far from where I live that practices regularly, and doesn't really bother anyone.

I'm fairly certain that there have been no tank related homicides in living memory, and the only two tank related crimes I can find news reports of involve a tank being taken from an army base for a joyride, and Killdozer, which injured no one (discounting the operator committing suicide), and was home-made anyways.

The thing about crime is that criminals instinctively want to hide what they're doing. Handguns are about a million times easier to hide than a rifle, or even a sawn-off shotgun. Having this bulky, visible weapon hanging off of your back is an automatic deterrent to crime.