I've used most all of the chemicals Brownells has for bluing. The best one in my opinion for what you are doing is http://www.brownells.com/gunsmith-to...-prod1072.aspx
It is the most forgiving and requires the least prep work of them all. Stay away from brownells bluing salts unless you are prepared to go into it in a big way. They are extremely temperature sensitive and you can destroy your bluing salts bath very easily if you let the temperature vary even a few degrees. They also require a black iron tank that can't have been mig welded as the copper coating on most mig wire will destroy the salts. The Dicropan T-4 is another cold blue solution that gives a good blue. Good luck, and post pictures after you get finished.