How do you know how deep you can file for the point at the tip that holds the strap in place?
I've got a couple of buffalo horns, but I am afraid I'll file too deep.
On this buffalo horn I marked the end of the internal cavity, then cut off tip about 1” forward of that. Then drilled spout hole 1/4” dia. From the cut off end , I measured back about 1 1/4” and made a recess cut all the way around with a coping saw to the depth of the saw blade( aprox 1/8”)
Then using a file with a safe edge , started filing down (safe edge to that cut) and away from tip. As I got deeper into the horn with the file , Icould hear the sound change as the file cut.
It is realy best imo to just go at it until you get a feel for it by sound and feel. If you wish to pm me Ive got alot of in process picture of doing this horn. Just too many to post on a forum.
Others may do it differently but this is what I came up with. Generally speaking , buff horns are much thicker than cow horn btw.
Good luck with your project