[swaghauler]

The other "hidden source" of ammunition was touched on in TW2K13...Reloading. In the event of a major "event," I would be hitting Gander Mountain, Dunham Sports, or Field & Stream and acquiring all the bullets, powder, and primers I could get my hands on. I do have bullet molds in some of my calibers, but commercial ones are better. I can make primers (using fulminated Mercury and heavy aluminum foil wrap) and both black and smokeless powder, but the commercial stuff is way better (and safer).
At the height of my competitive shooting "addiction" (I couldn't call it a "career" as it cost me far more money than I won), I had enough reloading components to roll 75K rounds in any given year (I averaged between 30K and 50K rounds shooting IPSIC, IDPA, 3-Gun, and Street Tacticals). I can roll around 15K rounds now that I don't have time to shoot as much. A typical progressive reloading rig would cost about $2K with all the tools and other equipment you need. I can roll about 300 rounds of good ammo an hour on my Dillon 550 Press. Primers would be the biggest problem in a crisis.
I don't understand why the Walking Dead didn't just have the characters grab a reloading press and components in one of the episodes. There would be REAL VALUE in having someone cranking out a thousand rounds a day during the apocalypse...but then they give the characters about a dozen full auto AKs in the show. The odds of there being that many NFA/Class 3 AKs in a single area are simply ASTRONOMICAL. Those should be tri-burst M4's and A2's picked up from dead soldiers, NOT full auto AKs. To make it worse, Rick is actually carrying a full auto AK-74! There might be (at most) a hundred of those in the US. Most in manufacturer's vaults. They should just have used semi-autos. That would be realistic in the US. I guess the problem is that the (not very gun savvy) producers think that Americans can just walk down to the local sporting goods store and pick up a Class 3 weapon.