My opinion is that the sheath is a brown button Heiser, based on the very blunted stone flap. I believe all 3 primary makers Moore, Heiser and Johnson, had their own style of finishing the end of the tab. This one speaks Heiser to me.
Moore style
Heiser style slightly rounded/blunted
Johnson style more blunted
I know that there are exceptions always between Heiser and Johnson tabs but this Heiser sheath below IMO is a dead ringer to the subject sheath
The back of the Heiser above
Regards, Sam