I'm no pro, and probably make things more trouble than they need to be, but here's how I do it:
I hollow out the burr to accomodate either just the bolt head or even the brass bevel depending what I've got.
I use a drill bit and a dremmel tool to get it just right. Keep the windows open, burning antler stinks.
I cut an allen key to fit in the bolt and stick out 1/4 inch. I epoxy it in with concrete/metal epoxy, let dry. I then drill into the burr with a drill bit slightly smaller than the hex key so that when I force the burr onto the hex key/bolt...it is a tight fit and I have to tap it in. More epoxy where the bolt head or brass bevel fits into the burr and let her dry. I havent had one fail yet.
You can stain the outer edges of the burr to look fresh if it is a worn out bleached burr. I use leather dye, but you can use wood stain too. Heres a set that was pure white that I fixed up....