I got a new GP100 in 357 mag. It is shooting well. But I am getting a little lead in the forcing cone and about 1/8" into the rifling. The rest of the barrel is spotless. The forcing cone is really rough and there is a distinct ridge all the way around the cone right before the rifling. I am pretty sure this is were the leading is coming from.
What would be the easiest and cheapest way to correct this? This is my first time reloading for a revolver also.