I have been running a Bully 14 tooth driver. I was look at the drum today. I have not been using a snap ring for a Bully driver. I have a new 13 tooth Bully driver coming. I will make sure and use the correct snap ring. I have read this can cause trouble. I don't know how I ended up the one I was using. May have been some of my trouble when I tried to run them leading.