I bought this bcg from Brownells and it is part #dd9300c,
Email Brownells CS and see if they well replace it. Some carriers well have rough machining on the exterior in the non contact area, that's 80%+ of the surface area. Hard chrome makes this more visible than phosphate.
The carrier bore were the gas rings seal needs to be perfect and the four rails that support the carrier in the upper need to be perfect, the rest not so much.