On the other hand the drop could indicate that all those who want guns have in fact purchased them. I own all the guns I want and am not in the market for more. (I would like an automatic weapon for when law and order breaks down but cannot legally buy one.) Secondly, a good NEW gun can be expensive and the economy is bad with more out of work than the statistics indicate.
I wouldn't worry too much. When this day comes, they'll be laying all over the ground.
Full auto is waaay overrrated—semi is the best. If you want full auto, go to Slidefire and try that add-on.