During one of our last gun control threadcraps, I mentioned that some of the numbers about guns in the US are hard to reconcile between sources, because while gun ownership rates are either holding steady or in a slight decline, the actual number of guns owned has risen pretty steeply. i.e. if you just take the number of guns and divide by the number of people, that will incorrectly tell you that everyone in the US has one or more guns, because the US currently has more guns than people. The truth is, more-or-less the same percentage of Americans have owned guns for decades, but the new trend is that some are now stockpiling them.
Scientific American now has an article about this gun-stockpiling phenomenon and an overview of the data/demographics behind it.
The short, broad-brush answer to the first part of that question is this: men, who on average possess almost twice the number of guns female owners do. But not all men. Some groups of men are much more avid gun consumers than others. The American citizen most likely to own a gun is a white male—but not just any white guy. According to a growing number of scientific studies, the kind of man who stockpiles weapons or applies for a concealed-carry license meets a very specific profile.