Loosely translated, Smart people invest in guns before the threat of a ban. If said ban goes into effect you sell gun supplies for an exhorberant profit. I'll have to dig up the article I found from the 90's that talked about gun sales going up before clinton's assult weapons ban.
Adding to sales is the worry of social and economical collapse. Despite how the media spins gun facts, most people aren't stupid. They know that if it ever comes to it they will be responisble for their own survival. During the awful ice storms a couple years ago I was definatly happy to gave my gun with me all the time in case I needed to hunt or defend myself. When the SHTF, the GOV is nowhere to be found.