They work very well for powder horns! Made two myself, working on two more, and I know other members of the forum have used buffalo horns too.
They have a different texture than cow horns. Take more work to get cleaned up, but are easier to work with after that, IMO.
Crazy Crow carries them, as do others:
[url]
http://www.crazycrow.com/Merc...PROD&Product_Code=1913-001-100&Category_Code=[/url]
Here are pics of the first one I did. I went for "elegant simplicity" on the second one:
[url]
http://www.muzzleloadingforum.com/fusionbb/showtopic.php?tid/174833/post/174833/hl[/url]//