what is a person to use to clean off the tarnish or discoloring from burnt powder residue on a c-nickle finish on my traditions 50 cal Buckhunter?

You can use a very fine grade steel wool or brillo and a heavy coat of gun oil. If you use too coarse of a steel wool you could scratch your finish. While scrubbing off the tarnish make sure you have a consistent coat of gun oil on the area.

Holmer,

I have used Flitz Metal Polish with great success. When regular cleaning couldn' t get it Flitz has.