Thanks everybody, Ronald I used Brass black by birchwood casey. I purchased it from Brownells, I am very pleased with it so far.
The brass must be freshly sanded to apply or it just does not blacken the brass. Next I hit the brass with scotchbrite by hand to age it. http://www.brownells.com/1/1/38935-brass-black-brass-black-birchwood-casey.html