Since you are using antler rather than horn, here is how I did it.
I put the antler up against the forestock flush & draw a line around the horn against the barrel channel. Take it to the bandsaw & cut the center out leaving some extra to file down. Then I drill two 1/16" pin holes from the end of the antler into the wood of the forestock, parallel with the barrel. Take a piece of SS 1/16" rod & put in the drill press & spin it while sanding it lightly with some 220 paper to give it some small ridges to grip the epoxy. Put epoxy or accraglass on the horn & pins & in pin holes & push the pins in. Put a small clamp across the forestock about 3" from the end, put rubber bands from the clamp over the horn cap & back to clamp to hole it snug against the wood. Let it sit overnight & then take the bands off & staart working it down with files. I put one on this way about 15 years ago & it is still on there & no issues. You definately won't wear it out.
