shooter is looking at a 7mm mag, and just how many thousand rounds is he gonna shoot?
Contrary to popular belief a stainless barrel will rust! That is unless you opt for something made of 17PH4 re-arc melt stainless steel. Not that it matters much here, but chrome moly steel is a little more stable, and will machine more accurately if done right. If your going to be shooting up near the Artic Circle, the typical grade of stainless is not what you want. It's in the nature of the metal itself. Most folks feel that a 4xx series stainless steel will handle heat better than carbon steel. It will, but nothing like they think it will. For that application one would want 330 or series 349 stainless steel, and neither one fits the usage application here very well as they are soft, yet very tough.
What one might think of doing, is the electroless nickel plate the barrel's O.D. It comes in two forms. One is the NP3 process, and comes out finished. Goes on extremely accurate. Not super hard, but still about a 43RC. Has about a 70% rust resistant factor. The other is the standard process, and is hard. About 90% rust resistant. The finish looks like bead blasted stainless steel, and is pretty smooth. I'd go with the NP3 process because it's ready to go as soon as it's cleaned up. It can be plated as thin as fifty millionths. Still I would never plate the bore.
gary