If you are burning corn or a corn/pellet mix like I do, the corn must be below 15% RM, no exceptions or it will cause carbon / creosote buildup. As the kernels carmelize in the heat of combustion, they give off moisture so it has to be dry shelled corn. The corn I burn is way under 15%, in fact the corn I run is at 10%RM or less and the drier it is, the hotter in burns.
if you get your corn from the local elevator, it will be 15% RM or less. Reason is, corn over 15% RM in storage will mold so the elevator dries it down to 15 for storage (and charges the grower for the fuel to dry it down). That is called docking. When a grower delivers corn to the elevator, the elevator probes the load for RM before it's even off loaded. I get my corn from a guy down the road with his own processing plant and the corn I get is exceptionally dry and it's perfectly clean too. No junk in it, just 100% popcorn fart dry corn.
You never want to buy corn direct from a farmer out of the field because chances are it's way above 15%, plus it's dirty. I've been running hybrid field corn for years and I've never had it come off at 15 or less. It's usually around 20, but I've seen it come off at 30 before. Elevator corn will be magnetically cleaned too. Combine parts can get mixed in the corn as well as nuts and bolts and you don't want your feed auger finding that stuff. Finally, elevator corn will have earwings in it and they need to be separated out. the corn I get has nothing in it, just corn.
If you want to buy from a farmer, I suggest you invest in a moisture meter that will tell you the RM. I have an expensive Delmhorst meter that cost around 500 bucks but there are cheaper ones on the market, just not quite as accurate as mine is. The one I have is accurate to within 1/10th percent of moisture but I need that, you don't. TSC has inexpensive ones I think.
My burning corn lesson for the week....