I had picked up some black stove pipe last night so I could finish the heater tonight. I used the 55 gallon barrel my neighbor got for me. I assembled it tonight so I can measure the proper height for the heat riser. While it was assembled, I figured I ought to fire it up to test it. It smokes around the brickwork, but I kinda expected that as it's pretty much wide open with all the gaps. I will need to take it half apart to put in the full height heat riser and plug all the gaps somehow.
The back hole is the exhaust side. The front tube is the heat riser. The curled bits help center the outer part of the heat riser.