bull rings and bull nasel septum cutter

After coming across the bull septum cutter, I asked a local butcher if he had any old bull rings left over from his butchering process. This is the pile of brass and copper rings that he gave me. For those that don't know how they were used, they were installed into the animal's nostril to make him behave for the farmer during his handling. The nose is a tender spot, even for a large bovine.
The second photo shows the ring with the screw removed so it can be opened for inserting into the animals nose, "OUCH", that has got to hurt.
The last two photos are of a tool that was used to punch the hole in the septum of the nose to receive the brass ring. If you look closely at the photo of the opened ring, it appears that the ring, when opened, has a sharp point to it's construction. I believe that closing the ring rapidly could result in the ring puncturing the nostril all by itself. So, that being said, what is the need for a tool that punches an arched slotted hole in the nostril? I know by the markings on the tool that it was used for this purpose. Does anybody have any idea why they needed this tool?
My only guess is that (and this is only a guess) after using the punch on the animal, you can wait for a few days for the punched out hole to heal a bit before installing the ring, after all, you do have to reset the small screw back into the ring. Probably not a good idea to attempt installing the screw when the bull is in an irritated state.