I have recently been looking at Koshirae in more detail and have come across a few Tsuka where Samegawa has not been used, they all just happen to be in Gunto mounts.
The first couple of pics could either be low quality same or another material, The second pic comes from a Amahide blade on the UK to-ken society sword register. Finally the last couple of pics come from a Tsuka currently for sale on Ebay.
What is the material used, it is described as doe skin or leather? and is it only used on Gunto, maybe because of a war time material shortage?
Does anyone else have examples of this to share?