The on-sale date is from the publication date recorded in the Catalog of Copyright Entries, Part 2, Periodicals, 1942, New Series, Vol. 37, No. 2.
Inside front cover.
Includes letters from B. D. Liles, Grace H. Romeo, Arthur Dandoy, and Theodore Elizondo.
This sequence does not appear in an online (apparently) cover-to-cover scan of the book. Possibly it appears in a different issue?
Its existence and reprint information are from the book "PRIMAL SPILLANE: THE EARLY STORIES, 1941-1942", (edited by Max Allan Collins and Lynn F. Myers, Jr., Gryphon Books, 2003), provided by Arthur Lortie, 6/29/2006.