Stats

300 million people.

300 million firearms in private hands.

But that doesn't mean everyone has one gun.  Some have none.  Some are JayG.

Ok, some liberal doctor group estimates that 35%-39% of US households have guns.

Ok, how many households in the US?  Census estimates over 115,000,000. 

So, .35 of 115 is...  over 40 million households. 

Good.

Of courset that total number is the hardest number to know.  Are there 250 million guns our there in public?  350 million?  Could be.  It's somewhere between those 2 numbers I'm guessing.