The present invention provides a liquid spray gun with several improved features, including (1) an air cap portion of a body assembly mounted for manual rotation on a nozzle portion of the body assembly between positions defined by stops and retained at those positions by friction; (2) non-cylindrical air passageways on air horns included in the air cap portion of the body assembly that provide improved shape and uniformity for the wide elongate stream of liquid formed by the spray gun; and (3) the body assembly through which passes liquid sprayed by the spray gun being molded of polymeric material and being manually releasable from a metal platform portion of the spray gun through which air is fed to passageways through the body assembly to spray the liquid.