Stickbender- I will certainly try to scrape/sand it and redo, but I'm not sure how far I'm willing to push it as it is my first piece and I don't want to redo the eagle, mostly... I know all about the preforms, by the way.  
I would encourage you to leave the horn as it is.  There is such a thing as "doing it to death".  Leave it as is, it's your first, and there will be only one first!  Like bows, just grab another and start over with a new vision.  
By the way, do you do pen and ink sketches or pencil sketches?  If you do, I want to send you some photos and have you render them in p&i or pencil for me.  If they work out, I'll have you do them on a powderhorn I have ready to be scrimmed.  I have a friend that is not long for this world and I want her portrait on a horn. 
Thanks, 
John