If this gun was produced prior to 1940, Shapleigh Hardware would have had no part of putting "KK" on anything. Shapleigh Hardware Co. arch rival Simmons Hardware used the "KK" theme exclusively. Keen Kutter was the first of the KK theme names, there was also Klipper Klub, King Koaster, korn Krusher, Koffee Krusher, Kool King, etc,ect. Shapleigh Hardware bought Simmons Hardware Co. in 1940. After 1940 Shapleigh did produce Keen Kutter and some of the other KK items.
I know nothing about Hopkins & Allen, were they in existence after 1940?
Is the gun on ebay pre or post 1940?