kamilaroi:

Acraglas perfectly repairs horn. I have used it myself to "rebuild" and repair horn {and Trolit and true hard rubber} buttplates. It is stronger than the original material, and can be dyed so it is absolutely impossible to tell the repair was made. It is also easy to shape and since it has no "grain", shapes can be formed that might otherwise be difficult in a repair situation due to potential for splitting.

It is the perfect repair aid for broken horn which otherwise, to those uninformed of this little secret, is an impossible task.

Only problem, now that this is public, beating a guy down on the price of a gun due to a busted buttplate will be a thing of the past...