Interesting Data Point

I have the day off, and during a spare few minutes I decided to run over and visit my favorite Merchant O'Death.  I noticed a sign I hadn't seen posted before, and asked about it, then asked if I could blog about it.  Their response, "It's there for public consumption.  Go ahead."  So I shall.  The sign in question:


What's the deal?  About 80% of the guns that come back due to reliability issues are not due to gun problems, but ammo problems.  The customer is advised to pick up a box of PMC or CCI or anything on the shelf not from WalMart, and try the firearm again, and then if there are still function problems, then bring it back.

The overwhelming majority don't come back.

Doing a little Violence Policy Center Research™ (a Google search), I turned up a few links looking for "WalMart ammo quality," like this thread from Cheaper than Dirt's Forum from 2009.  Excerpt:

I recently talked to a shooting range owner about this issue. He told me they had noticed more issues with ammo bought at Wal Mart (misfires) than ammo bought at other retailers. He had heard the the major U.S. manufacturers actually set aside ammo that wasn't perfect (i.e. discolored) to sell to Wal Mart at a discounted price. This person's info is generally accurate so, who knows? -- "Speed Biker"

The next few replies were in defense of reputable ammo manufacturers and their quality control, and that's what I've found over most of the web, but I like this gunshop, and I trust the guy behind the counter when he tells me that they're seeing people have a lot of trouble with Wally-World ammo not functioning well (FTF, FTE, misfires, etc.)  I don't know if this is a recent development, influenced by the massive ammo orders placed by the federal .gov, or what, but I found it interesting that it was such a problem that they felt they had to put up a sign to preemptively stop "warranty" repairs that weren't, in fact, warranty repairs.

Anybody have any similar stories?