I have noticed several times in regards to old mausers that they will be listed as having a dark bore.
I just purchased an old 98 locally today for $100. All the numbers match and the old relic is clean as a pin. I am not sure as to its origin but on top of the receiver it has a sliver of the moon laying with the open side up and there is a star just above that and the letters K.Hale 1941 under the moon. This is a very nice old 98 other than one thing and that being that the 28 3/8" barrel has what appears to be a bore that is very dark.
Does this mean that the barrel is junk? The rifling looks very sharp and there doesn't appear to be any throat errosion or pitting going on....its just dark. Can this be cleaned up and if so whats the best method or would I be wasting my time?
The star and moon probably mean it's a Turkish mauser. Some of the turks are 98 actions with small thread recievers, some of them are mdl 93 mausers, not 98's.
The bore is dark either because it needs a good cleaning, or because the bore is pitted. Just because it's dark doesn't mean it won't shoot acccurately. It might foul more quickly and need more effort to clean.
If it truely is a 98 action, then $100 for just the action isn't a bad deal. Also if the action is a small thread, you can use a remington take off barrel to re-barrel it.
I'd give it a thorough cleaning, see how the bore looks, then run a box of ammo through it to see how it shoots. You might just have a fine find. You also might have a donor action. Can't go wrong for $100.