If Bill Gates had a warship...
When people talk about the 2nd Amendment and its limits Libertarians are usually shocking both liberals and conservatives. Yes, conservatives like their assault rifles but how many would be pro automatic rifle legalization? And whats with the legalization of tanks and warships? Normally people who legally own guns are reasonable enough to not harm anybody except for themselves. (16000 suicides with legally owned guns a year) The reasons for not killing someone are numerous. It's a sin but some people don't believe in sin. It's immoral but some people don't believe in morality. And finally it's against your self-interest and someone who is wealthy enough to buy a tank knows a lot about self-interest. Whoever buys a warship to protect his own property would be responsible enough to use it properly and certainly more responsible than the governments of Russia or Pakistan or the United States...
I find this conversation to be a funny one... as if tanks and such items were legal tomorrow for everyone to own, that everyone (even your neighbor) would have the hundreds of thousands of dollars to go out and purchase one/or even want to.. just funny!
I strongly oppose the 2 cornerstones of your post.
WP says the official numbers are:
11,208 homicides (3.5 per 100,000);[3] 21,175 suicides;[4] 505 deaths due to accidental/negligent discharge of a firearm; and 281 deaths due to firearms-use with "undetermined intent"
Now compare to Germany with 80 million people: Death from guns (jumps up and down strongly): between 30 and 70. Legal + illegal weapons. About 750 suicides with guns.
So even if you say Germans are reasonable, the US people for sure aren't.
This too is an assumption not based in reality. If people can kill someone with a gun (yes, I take that example ^^) because of a branch of a tree is hanging over the neighbors fence, then those completely sane people (up until this moment) would also use a bigger gun to blow away the house of the target.
Most of all homicides are gang related. Germany has yet no gang structure like the US although its developing in the last years. Gangs developed in a certain climate that involved the war on drugs, a certain welfare policy and ethnically segregation. But mostly the War on drugs. A war that wouldn't occur in a free society.