Well Schucks
I'm no help for OP. I wanted one of the Miroku '66s, but my Mad Money just couldn't go the Tariff.
However, I do own and shoot Five Uberti Brass Rifles and they did not arrive with any sort of "coating." Couple of folks have mentioned recently, their newly made Uberti Brass rifles arrived with a thin, peal-able, plasticie film on the side surfaces.
Caution!! People are Still Hazardous to Yer Health