This news article states that civilians in the United States own almost 400 million guns. That is 100 times the number of firearms in the hands of the US military, and 400 times the number that are owned by law enforcement agencies.
(Please click pics for bigger and better.)
Of course, a great many of the guns civilians own are for plinking, shooting small game such as squirrels, or collectors items that are held for the historical value. Even so, it is pretty impressive. Especially so considering how low the crime rate is in the US.
I think we can do better, though. What is to prevent us from reaching a billion?