Gunlocke typically put an inset round bronze medallion on the inside of the right rear leg about the diameter of a nickel. Other office furniture companies made similar waiting room chairs at the time.
Gunlocke would be my first guess but many companies made chairs in this style: Boling, Murphy Miller, Jasper, etc. They are basically Americanized versions of Danish armchairs of the period, Wegner's "round chair" in particular.
