Husbands new horse, Hondo, is undecided. LOL. Old owners called him a buckskin. Someone at the barn told me he wasn't a buckskin. He was a dun. In my experience all the dun's I've seen have been the lighter tan colors. I have seen some terms referring to a 'dunskin'. I looked on the IBHA and they have a dun as the darker color, buckskin as lighter. Duns are said to have the primitive markings, the dorsal stripe, shoulder stripes, and striping on the leg. While I believe the color associate should know what their talking about, lol, he just doesn't match either. Hondo only has a dorsal stripe.
You would register him as dun, I would assume, with the IBHA because he has the dun gene. You could contact them too and ask. I know there are dunskin registered with the IBHA (SBR Formula One, for example), but I don't know what as.
Its a waiting game! He's a quararab, so he'll fill out some, but won't have the butt my QH has :( But that's ok. I can't wait!!!! I have no patience! We also have a b/w paint, as well, that is gaining weight.