Wet bituminous fines jamming up my auger caused me problems on more than a few occassions until I figured out where the rain and snow were getting into my coal bin. I get stoker coal delivered, but it seems that every coal load is a lot of fines. For the most part, it doesn't cause too many problems unless it's wet. I'm not sure what constitutes "wet" coal as we get about 24% moisture in our coal right out of the ground -nor would I know how to test it... except, "Yup, there goes the shear pin, again." The dryer fines don't seem to cause me problems with the auger or with the fire. If you decide to try it, make sure you have extra pins standing by!