Have been reading about the Grohman belt knife after reading the previous comments, looks like a great design. Interestingly, my dad has an old Chicago cutlery knife he’s had for decades and despite trying many others, he always goes back to using it over other designs. The Grohman seems to have some similar design features in the blade to his trust Chicago Cutlery and as you said, I’ve always marveled at how well it zips through hide without catching.
I believe his knife is the Chicago cutlery BT-94, it looks very similar to the one in this post, except his is so well used he’s sharpened away all the serrations on the “break through tip”.
This rare vintage hunting knife was made by the old CHICAGO CUTLERY company probably back in the 70s. U.S.A made of course. This one is more rare than the it has the Break Through blade they didn't
www.worthpoint.com