Hard to tell from the photo, and I'm currently away from my copy of the SCSW3, but I'll guess that it's a per-war M38, probably from the mid-to-late 20's. I'm basing that on the apparent brass medallion grips and large-knobbed ejector rod, as well as my distant recollection of sn's. That thing is very much like old Herman Goering's S&W. You didn't happen to find it laying around West Point by any chance, did you? -S2