I put together an underfolder using a 1973 Polisk PMKMS kit.
The kit is parkerized, not blued or painted.
I hadn't even realized that the Polish used a parked finish on AKM's.

Anyway, the bolt and the carrier have a different finish.
I asked a local AK builder about it, and he said that different hardness steel parks differently.
I have no idea what kind of finish this is, but it certainly isn't etched like parkerizing.

Here's a pic of the finish on the carrier:




It's a medium grey color with fine swirls of a darker grey.
I think this is a really neat finish, but it creates a dilemma for me...

I need to change the gas piston to make 922r compliance.
And I really want to keep this original finish.
If it was blued or parked and painted, I'd just polish the carrier.
Is there a way for me to preserve the finish on the carrier and have my fancy US made piston?