I am looking at taking another stab at producing 43 Spanish cases for my Remington Rolling Block and have read suggestions that 338 Win Mag brass could be used by cutting off the belt and reworking the rim of the case. My question is for the machinists in the group, how would I mount one of these tapered cases in my lathe? I have a 3-jaw chuck, and flat base plates to mount things too. My tool mount has a swivel top so I can mount and run tooling in a taper for about 6", which would allow me to easily follow the taper of the case with a cutting tool.