I was loading some .38 special ammo tonight, and as always, I set the powder measure for my charge and threw a few charges after it was set just to check. First couple of charges were OK, and then powder stopped flowing through the funnel.(Dillon 550).
Took the powder dispenser apart, and sure enough it was blocked. A spider had gotten into my powder measure since the last time I used the press, and made his way into the funnel. He was still alive, (fixed that) so he must have been swept into the funnel with the first few charges. Anyway, I reloaded the hopper with powder, and started getting erratic charges.
Turns out, the little bugger left me a present, in the form of a strand or two of cobweb, and the powder was sticking to it.
Took the whole thing apart again and thoroughly cleaned it, and no more problems.
Never heard of that before, but it had me scratching my head for a few minutes.