If...you have a drill press, I'd make an intermediate size elliptical sizer ball with a file in the drill press, finishing it to the smooth polished finish to reduce friction thus force.Yes, store boughten expanders are hardened, but a plain old grade 5 heat treated bolt shank is plenty hard for the job at hand and polishes easily. You will need an 8/32 or 10/32 tap if you want to use it in your die...or leave a good shank on it, use your drill press quill and chuck and clamp the shell holder in your drill press vise. Anneal the hell out of the neck and upper shoulder of your .308 cases. Lube and expand in two steps. You don't have buy every proper tool, every time.
I really appreciate your last sentence. We all can think a little deeper and use what we have to achieve the same result in so many ways.
