TJ, I make my own lump charcoal as well. I have access to oak pallets and cut them up so that they pack well and off-gas well. Speaking of that off-gassing, I turn that back to the base of the barrel with a couple of 2" elbows, nipples, and the appropriate length pipe, so that helps minimize the cooking fuel. I use a piece of culvert that is larger than the 55 gal barrel and burn softwoods in it as fuel. Also, I use a blower from a downdraft range to add O2 and increase the temps...which reduces the process time. Once the flame goes out at the end of the pipe, you know that all the distillates have been cooked out and the charcoal is pure.

It's awesome cooking on your own charcoal!