This won't apply to your current project but have you ever considered melonite coating? I built a 280 ak for a guy in Alaska and I don't know a harder man on a rifle the him. He is an avid sheep hunter and packs his rifle miles and miles. The coating is holding up really well. You can also use the fancy coatings ove melonite. The sako I did for myself is unbelievably slick and a mod 70 would be also.
