Just some notes about the barrel kiln. This is actually a photo of me drilling holes into my first barrel kiln, but after yesterday's firing I felt the need to comment about drilling holes into the barrel.
This barrel burned really well, I believe, because holes 1/4 inch were drilled approximately every 6 inches in the middle section and the bottom section of the barrel. I also drilled several holes in the bottom of the barrel. So much wood is packed into the barrel during the firing that without the holes I think it would take forever for the fire to burn and quite possibly just burn out due to a lack of oxygen.
I say this because in my newest barrel kiln that I fired yesterday I wasn't able to drill enough holes because my drill batteries ran out of juice and as a result I had more smoke than fire. I won't know how well the newest barrel kiln fired until I can check it out after work today but I firmly believe, after my past two firings, that the more holes the better and what has worked well for me so far has been holes drilled appoximately every six inches around the exterior of the kiln.
Regardless, I'm drilling more holes.