You could always lap the forcing cone, and/or the barrel tooI am a firm believer that the roughness of the forcing cone and barrel can have a significant impact on the performance of bullet coatings. While I have had great luck with coated or plated bullets in most of my guns, I have a Ruger Blackhawk that simply did not work well with either coated or plated bullets. The coated bullets leaded the barrel quite a bit. I saw evidence of plating failure (small shards of copper, and leading in the barrel) when using plated bullets, even when kept to 1000 fps. The forcing cone had visible machine marks on it. I have since started using Zero jacketed bullets and have no problems. I figure once I shoot a few thousand rounds through it, it may be worn smooth enough that I can revisit coated bullets.
edit: Random 8: call/email MBC and I'm sure they will make this right, if you have already...never mind