Some info verified using a DCM scan (http://digitalcomicmuseum.com/)
The on-sale date is from the publication date recorded in the Catalog of Copyright Entries, Part 2, Periodicals, 1940, New Series, Vol. 35, No. 3.
story continues in Blue Ribbon Comics (1939 series) #6 (September 1940)
Originally credited Mort Meskin. Compared with his signed story in #6, this is not him, but George Storm. Compare also with Storm's story in Hangman #19, with long and lively inklines. He is credited on this feature by Jerry Bails' Who's Who.