When you get them still on the skull don't just cut them off right at the end. Cut them so part of the skull is still attached, as an extension of the antler itself. Use the solid end to cut your threads in/on, once the pouring hole is drilled you should have a pretty solid tip.
One thing you want to stay away from is old antler that has turned chalky White, I have found that it is really soft no matter what part of the antler it comes from.
Caribou is another that is really solid and has a nice color, cleaned up it looks a lot like Ivory. This may sound strange but the trouble I have using Caribou, Axis, Sika Deer, etc... antler is that it wasn't available in the area where the style of horn that it is used on were made. Just one of my little Idiosyncrasies.
Tim
PS: Funny...I don't have a problem using electricity though
TC