I would say dry house, to finished handle, for the Unbrako brand anyway. The pictures in the add are my experience with air dried hickory, not so with kiln dried handles. I wish more people could experience an air dried hickory handle, It's nearly indestructible. Thanks again, Steve for the research.
For the sake of avoiding warranty returns of loosened heads I wonder if Axe makers did a quick kiln-dry to their sourced out air-dried material just before assembly. Certainly any green piece of wood is going to suffer 'big time' from forced dying but what of an already air dried piece? Not much moisture left in there to boil off or steam rupture the individual wood fibers, and the haft would temporarily shrink to it's smallest dimension just before it was fitted and wedged. Any chance this is 'best of both worlds'?