I have a matching 1980-dated parts kit that has a matte gray finish on it. Came that way from the importer when I bought it 5-6 years ago.

Any significance of this finish? I think I read once on the forums this may have been on "Polish Navy" guns, but haven't seen that info since then.

I have a 1972 underfolder from intrearms that came with that gray parkerized
finish on it and the color was just...funky. Great little gun though but I couldnt
handle the finish so I had it gun coated. I figured it was just a cheap ass park
finish. I've never heared anything about a Polish navy finish but what do I know?

I bought quite a few PMKMS underfolder kits that were mismatched & there were more than a few of the parts that were of the flat grey you posted about. Years ago, there was a dealer who sold parts kits that were light grey parked completely, including the mags; must be a reason, but I don't know what it may be. All Polish guns were parked under the paint that was applied after assenbly!