Seven Men's Sins was first published by Harper & Brothers, 1929 as Only Seven Were Hanged. There are two versions of the Randall edition which is undated but circa 1950 with the text block identical and two different covers. No priority. The horse cover's artist is unidentified but the yellow cover with man has signed art by Harold Bennett. Bennett illustrated a number of Canadian pulps in the 1940s.
My new blog about LA Bantam is now open for business here.