Actually, they do. I have 3 WalMarts within 10 minutes of me and they haven't quite depleted their stock . . .yet. True, WalMart central has decided to not order any more but each store still has their supply. They, of course, have .308, 30/30 and 30-06 and sell the rifles, to boot. They never intended to stop rifles and rifle ammo but several of them still have some pistol left over. In fact, WalMart is the ONLY source of Federal 130 grain 38 SPCL +P - the round that looks like it was loaded backwards into the cartridge. None of the LGS have ever carried it.As to big box stores, forget Walmart. They don't even sell/stock handgun ammunition any longer. Same for rimfire.
Back when Walmart sold handgun ammo, I used to buy a box just so I could check out at sporting goods and not have to stand in line at the front of the store.The funny thing is, a friend told me it was a good idea to always buy a box of ammo here and there just to keep the cartridge manufacturers running and to pile up ammo throughout the year. Now I can appreciate why he does that. Lol