All home bluing falls under the heading of cold blue. The best of the bunch is Brownells Oxpho-blue, which will give an acceptable finish if you do your part. What's worked the best for me is completely degrease everything with something that doesn't leave ANY residue. Also, get a pad of 0000 steel wool, and completely degrease it as well. Heat your part with a blow dryer, and then apply the Oxpho with the degreased steel wool (don't forget to have clean, degreased gloves on, you finger prints will goof this up). You'll have to apply several coats, reheating as necessary. Really go after the parts with the steel wool, you won't hurt them with 0000 (4-ought), and use plenty of Oxpho.
The end result looks ok, but will NEVER match the durability and depth of color of a hot blue job.