Just getting caught up with this wonderful thread.
And I gotta say... that stamp is way cool, and by posting it you inked an answer for me.
Being a Navy man, I was curious about the stamped anchor found on a few Golden Age books. So I kept some images of books I'd admired with it, wondering about the stamp's backstory and how/why they came to be.
As a result of your post, I did a little digging and apparently the anchor stamp with an individual's two initials was a promo offered during the Don Winslow of the Navy radio show. The excerpt below is from an old radio program titled Radio News Tower published by Radio Station WOW, Omaha Nebraska, with a print date of July 1, 1938. It mentions the stamp as a special offer on WOW.
Anyway, hope you don't mind me posting images in your thread. Yours is a good one. And I echo the thanks for sharing your nostalgic time capsule with us.
Glad you are enjoying the thread. NICE Action #15! If you look back a couple pages in the Fawcett thread some one showed an early Whiz with this stamp on it. I'm sure most people would have no idea what it is. Earlier in my thread I posted some more early Don Winslow premiums.