When I made a horn or antler measure, I drill out the tip with as large a drill as the antler/horn will permit. Then I use a rotary file and a 3/8" round burr in the drill press to cut away the horn out to the edges of the measure, making it as thin as I dare. When I have finished with this, I pour in powder to fill it, then dump the powder into a scale and see how much it throws. I adjust by going deeper to increase the throw, and cut away the top to lessen the throw. Occasionally, I drip beeswax into the cavity to diminish the throw.