Bernie posted a photo of a 2-5 in "This Old Randall" thread last week that came in a sheath with an odd brown painted metal snap. Based on the knife and sheath attributes, the era was narrowed down to circa 1960 give or take. The sheath was assumed to be Johnson because of the Randall stamp.
About 4 years ago I picked up a circa 1960 3-6 that had been pitted and cleaned by the shop. I normally wouldn't buy a cleaned knife, but this one was mated with a very unusual sheath that had brown painted metal snaps and just a "3-6" stamped on the back. The sheath matched up pretty close to another BB Johnson 3-6 that I had (Including what seemed to be the same "3" and "6" die stamp), and my initial thought was that it may have been a prototype that Johnson made up before Bo brought him on as a steady supplier:
Moving forward, another circa 1960 3-6 came up on e-bay 3 or 4 months ago and damned if that sheath didn't have similar brown painted metal snaps! The kicker was that in addition to the "3-6" stamp on the back there was a Heiser stamp! That changed my mind about who made that previous 3-6 sheath.
Now Bernie comes up with another circa 1960 sheath with a similar snap (Although Bernie's snap might be a tad larger).
Many Randall collectors are aware of the fact that the shop and Heiser ran out of Brown button snaps in the very early 50's as you see a number of Heiser sheaths from that period with alternatives. From the three circa 1960 examples that have surfaced, there might have been a short period of time around 1960 that again the supply of BB snaps were depleted.
Footnote and food for thought: I think I remember hearing or reading that on good authority Heiser never sent the shop any unmarked sheaths and the shop never stamped the model / blade length nor the Randall logo on sheaths, but if they did that would explain why we see Randall logo stamped sheaths that seem to predate Gary's 1st contact with Johnson in 1962 (Gaddis 224).
Best,