My supplier had over a million Federal primers ordered in 2013, directly from Federal. He only got about 400,000, and then Federal advised him in October that they couldn't fill the rest of his order, and they weren't taking any new orders until after the first of the year. They just can't keep up with demand, since there is only so much manufacturing capacity. They also supply primers to other manufacturers, such as Hornady and myriad smaller companies.
Hope this helps.
Fred