My observations on this issue:

1, I have never heard of Clayton Howard and would need some serious proof before I started to think that he was a sheath supplier to Randall.
2, I don't see a difference in the button color between Johnson and Heiser. I once thought the same but after looking at obvious Heisers or Johnsons I can see both dark and light from each maker.
3, Personally, I think Heiser may have made a small amount of Randall stamped brown buttons but I also think Johnson made the majority. Perhaps the date for Johnson needs to be looked at more.... Joe or Ron: Can you guys think of another way to get more info on this?

Gary