alamosa said:
How do you make the large end round so you can fit a round plug.
The best I've been able to get with a buffalo horn is
almost round. Boiling water works pretty good on cow horn, and hot veggie oil is a snap as long as you are careful not to over do it. But buffalo horns are not so easy, partly at least because they are thicker. Once I get them as round as they are going to get, I just carve the plug to fit their shape.
Boiling water works to get them soft enough to shape, but it takes a long time (20+ minutes). If you use oil, take care not to scorch the horn... leave it in for only a few seconds at a time then check to see if it is soft enough to slip over your form. I use a candy thermometer to keep the oil temp at about 300-325. Pull it out of the oil immediately if you see tiny little bubbles coming up out of the horn. You'll want a good pair of gloves for handling the hot horn. Even with all that, and a proper sized form, I think you are going to find that the buffalo horn doesn't perfectly conform to shape. Close to round, mind you, but only close.
I've done as Roy mentioned and split at least one horn by pushing too hard to get it on a form it didn't want to fit. Best to have a couple of forms ready, one that you think will fit and one a little smaller than that one. I tried to find an old wooden baseball bat to chop up for use as forms, but folks around here want money for those things. Ended up using a lathe to turn down a scrap piece of 4 x 4. You want one with only a little taper on it; too steep of a taper and the horn won't stay put.
That stair railing idea of Karlk's is a good one.