An anodizer for the government does the following mil spec treatments and I would like to know which is used on the AR15 if any:
MIL-A_8625 Type II
MIL-A-8625 Type III
Bushmaster uses a "hard anodize finish with a nickel acetate final seal coat"
BTW - be sure you specify "black dye"
The old original gray was milspec 8625. I don't know about the black.