I've spent alot of time gazing at sheaths and their construction in an effort to make sense of who made which sheath. It makes ones head hurt sometimes. Here are some photos of five different Model 7's with brown button sheaths. The three on the left are all stamped Heiser. The two on the right have the Randall Made stamping. All five have the "tooled ridge" or groove.

Close examination of the tooled groove shows that it always follows the stitching, and is only where stitching is on the sheath. With this in mind, it seems to me that this tooled groove is likely imparted onto the leather edge by the pressure foot of the stitching machine. I would assume different stitching machines apply different pressure patterns, as this same type tooled groove is not seen on later known Johnson or even Sullivan sheaths. I wonder if this groove could be unique to the stitching machine used by Heiser?

The next photo shows the backs same five sheaths. The die used to cut out the leather varies quite a bit in shape. I wonder if there is anything to be discovered here with respect to the timing of use of specific die patterns? Since the time that Johnson was supplying sheaths overlaps with that of Heiser, it seems likely to me that Johnon's dies for cutting the leather would have been different in some way.