Saad, the flats on the barrels will be blacked along with the whole barrel; it is that sometimes the blacking is polished off on some guns and not on others. I'm sure you are aware not to use modern 3" cartridges in this gun. It should be o.k. with 2 3/4" mini magnums if CIP approved. Jeffery had all his guns made for him in the Trade and never actually made them himself. Lagopus.....