One thing I recently saw online was a 624 with a recall stamp on the label circle C in red. It was interesting in the description the owner noted that on the right side of the grip frame under the grips, along with some other stamps was a circle C also. I would say that hearing that, would indicate to me for revolvers that don't have boxes, look for a circle C on the grip frame under the grips. S&W has always had some sort of a stamp to indicate a gun has been checked or had work done by their shop. In this case it would be logical for them to stamp the circle C on the grip after the inspection done and the gun was to go out. That's certainly worth looking into, I would think.