As I mentioned above, I recommend copper wool (made for cleaning pots) over steel wool. The copper won't scratch steel.
As to ammo, that Danish rifle is not chambered for .30-40 Krag and ammo is nearly impossible to find. 8x58R cases can be formed from one of the "universal" cases with the same base diameter as the .45-70 (.45-70 cases themselves are too short).
Jim
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