Hell, this pipe has me thinking in lots of ways.
The "o-ring spot" just looks to me like a spot that naturally would hold one. Almost as if it was a known air gap. Not saying it is, only that it LOOKS that way. A proper sized o-ring would certainly fit there, and would likely act, if nothing else, as a crush ring type gasket. Or maybe not!
I have a Grabow "Lark" that has a small hole in it, right at the bowl / shank connection. I don't know why it came about. Burnthrough is doubtful, as it was very lightly smoked. Or, maybe it burned through an already thin spot. In any case, it COULD be drilled through cleanly and some sort of metal tube inserted into it, and flush filed down on the outside to have a home-made carb. May try that one day when i am bored.
