According to user shoofly, Street & Smith art director Charles J. Ravel created the cover art for SHADOW MYSTERY #312 to #316. The dates of these issues begin with February/March 1947 and run through October/November 1947. I attempted to contact user shoofly to learn where he or she found the information about the cover artist. Unfortunately, I have yet to receive a response.
If one looks at the covers to SHADOW MYSTERY #317 to #320, dated December 1947/January 1948 through June/July 1948, the five covers that shoofly has attributed to Charles Ravel are very similar in style to these four covers. The cover art for SHADOW MYSTERY #317 to #320 has been attributed to artist Walter Swenson. The artist's signature is noticeable on three of the four covers in question -- #s 317, 318, and 319. As #320 has a black background, no signature is discerned.
Why did shoofly attribute the cover art for SHADOW MYSTERY #312 to #316 to Charles J. Ravel when the style of the artwork seems so similar to Walter Swenson's covers for SHADOW MYSTERY #317 to #320? Until shoofly can present some evidence, perhaps only "The Shadow Knows."