My local Walmarts (both of 'em) have been out of ammo with the exception of the odd box or two in odd calibers for weeks. On March 24 I placed an order for .38 special and .357 magnum ammo with Midway Sales. I was told that the product was on backorder and to be patient. On May 1st I inquired about the order and they said delivery by May 15. Here it is, May 22, and no shipment. Also, Midway now has stopped accepting orders for nearly all ammunition. I have .357 magnum ammunition on backorder with Cabelas (they say 8 - 10 weeks but I ain't holding my breath) and 45 ACP on backorder with Bud's.
So, in a sentence, yes, there's not only a shortage of ammunition, there's a panic. What's happening with ammo sales is quite reminiscent of the gasoline panics of the 1970's. And, I suspect, it is a panic which -- like the gasoline panics -- is fueled by irrational reasons. Since the election there have been numerous rumors circulating widely about government restrictions on ammo sales, requirements that ammunition bear serial numbers, heavy taxes on ammo, etc. These have all been shown to be totally false or, in some cases, based on a grain of truth but not on any rational evidence that the feared event will come to pass (i.e., there are some state legislators who have introduced bills at the state level to require that ammunition have serial numbers. These bills have all died or gone nowhere). Moreover, they have flown in the face of evidence that our Congress is downright hostile to gun regulation (it just passed legislation allowing for concealed carry in national parks) and that the Administration is indifferent to it (notwithstanding a couple of comments made by a couple of appointees early in the Administration, neither the President nor any of his officials have asked Congress to adopt gun regulation legislation).
My guess is that this panic, like all others, will pass eventually. I can't predict when that will happen but, in the meantime all of us have to pay the price for the irrationality of others.