I agree with the Lewis Lead Remover idea and that bullet size/hardness may be issues.

The circular grooves in the forcing cone are from either a burred reamer or chips that got caught during the reaming operation. The factory doesn't single point forcing cones. Lapping the cone is possible. A brass cone with a matching taper can be used. I generally cheated and glued a piece of emery or crocus cloth on the taper plug.

Also as noted, someone who does this stuff for a living (or has the skills and over invested in a hobby) has all the tools and would probably do the job for less than it will cost you to get the tools. The factory is also good, but if measurements are within factory tolerances, they won't be worked.

Depending upon the specs of your cone, a single point tool might be able to clean up the forcing cone while keeping it within spec, but you'd be paying for pulling and reinstalling the barrel.