Never tried it as non of my billies have ever butted but I'd go down the squirt in the face track.Bagots have horns and any "Butt back" has got to be pretty hard to work.The main thing is to find out what caused it on the first place.
I bought a Bagot billy out of Glos market (when they had one)and he was more a swiper than a butter.I knew what caused this,too much horn grabbing and I stopped it.A year later he went to a new home but first I had to drop him off at a pick up place (remember ewhen you could still do that?)
I went to ask him out of the trailer with his collor and lead,he hesitated,and the "helper" immediately grabbed his horns...one years training up the spout!....boy did I let rip