How many guns are there in the United States?
Check it out:

While no one knows exactly, our most reliable estimates have put the numbers of firearms in the hands of United States civilians at 300 – 310 million, but I am convinced that number is no longer anywhere close to accurate. I suspect the true numbers are a lot higher.

In 2007, the Geneva based Small Arms Survey estimated that there were over 270 million privately owned firearms in the United States. This estimate is a very rough educated guess at best, but is often used as a starting point for discussion. A number of criteria were used to come up with this number, including gun registration numbers, expert estimates, household surveys, proxy indicators such as GDP and gun suicides, and comparison with similar countries.