Here are six brown buttons:
On the flipside, five have the Randall logos and one has the Heiser logo:
From the standpoints of overall quality and stitching patterns, I would guess that the five with Randall logos are all Johnsons. Yet (as I previously alluded to), the overall quality and stitiching patterns of Heiser sheaths varied over the years. Here's a pic of two Heiser sheaths (One marked and the other unmarked) from the late 50's when both the shop and Heiser ran out of brown buttons for the 2nd time. If both were unmarked and had brown buttons, I would assume they were Johnsons:
Did someone say this ain't going to be easy?