I have totally roasted my forcing cones and the face of the cylinder in my FA's and they still shoot little tiny groups at a 100 yards...So don't overthink this as a "problem that you need to throw a bunch or money at "unless" the gun won't shoot.
My 454 was pretty bad. And now I have around 9,000 rounds through my 475L and it looks like the forcing cone was cleaned with a triangle file.