Disclaimer: I sell the stuff and have thrown away far more than I have ever sold due to warp and twist.
Buffalo horn is beautiful material. It polishes up nicely and appearance wise it's hard to beat. I really like how it looks.
Having said that, it's not a great material for full tang scale handles. If it doesn't warp or twist when installed, it's likely to eventually twist with just time or especially with humidity changes.
It can used as scales on a full tang knife but you will want to use several pins to help hold it in place. And good epoxy.
Horn does work well in small pieces on say a folder (using screws to hold it in place) and it is especially good for spacers or accent on a hidden tang knife.
Think of a water buffalo and their horns. All this material comes from them and is cut, heated and pressed to "straight". It takes a set and often it will hold that set, often it won't and curls back up to it's natural state. You have to plan that eventually that horn will want to curl back to how it grew and build your knife with that in mind to hold the material where you want it.
To grind and shape, use a brand new sharp belt. If it gets warm when grinding, it's going to move -- a lot. Grind it, let it rest, grind it, let it rest. You won't be able to get it all done at once.
I love how it looks, hate how it holds up -- on a full tang knife.
I think there are about a hundred materials that work better for a full tang knife than horn. Just an opinion and it's free so take it for what it's worth.
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