The '309' shape has long struck me as a particularly Peterson-ish shape. That bears some explanation, I think. Specifically, the proportions of the cylindrical bowl are barely larger than those of the shank, creating this almost tubular effect. High shank thickness to bowl size ratios are a signature of Peterson's pipe shape aesthetics and I can't think of a shape that more embodies that than the '309'.
-- Sykes Wilford