Dana the Dane

Picked up some Corbon 44 Spcl ammo at a local Mom and Pop fishing/hunting shop to try out in my newly acquired Redhawk. It was all they had in stock, and looked like it had been there a while. It was not cheap, but what the heck, I do like to support local business. $36 for a box of 20 (ouch), but I do reload, so I would re-use the cases.
Took the Redhawk out for her trial run after an initial cleaning and inspection (a used 1996 model in pristine condition, except for a little oxidation around the trigger housing...only visible on disassembly...probably sitting somewhere for a long time) I was popping along through about 10 rounds or so, getting a feel for the gun, noticing I needed to adjust the rear sights. At about the 11th or 12th round I heard a faint pop. No bullet exited. A squib! (from factory ammo, no less!...I had had one of those in my .45ACP reloads when I first started reloading, which was a valuable lesson in double-checking everything when reloading). There was this greyish-yellow stuff- in cylinder, and all down the barrel. I could not get the cylinder to open. I had to force it open to clear the weapon so I could verify that it was a squib. More of that grainy yellow junk. It did not look like any gunpowder I had ever seen. It even got into the trigger assembly and gummed everything up. The pistol would not function at all. And there was the squib, about 1.5 inches from the end of the barrel. I had to remove the squib (obviously) and detail strip the entire gun to clean all of that stuff out. It was sticky as heck, and very hard to remove. I did get the gun back together and functioning later, but I did not use the rest of that Corbon 44 ammo. I pulled the bullets and saved the cases on the remaining 9 rounds. They all seemed normal when I dismantled them. I certainly was not going to use them after what had just happened.
Which leads to my question: What did happen? Does gunpowder go bad? Did it get wet? Disgruntled employee at Corbon? Has anyone else ever experienced this?
(unfortunatly, I did not take any pictures....)

Nutty Ned

You did say it was old, probably stored poorly.