Is it your starting rod that is making the mark or your ramrod? If it is your ramrod, I would file it flat since the barrel will keep it centered on the tip. If it is your starter, maybe you can use a dremel grinding tip to shape it like your bullet? I know many pointy lead bullets come with their own rod tip to fit them.
I used to get a ring when loading, I really don't think it makes much of a difference, but then I was not shooting over 100 yards at critters or targets.