I did a rifle with Brownell's Oxpho-Blue cream, inside and out. It looks a lot better that one might expect, but an awful lot of work went into it.
Oxpho-Blue doesn't produce a very good color with the metal at room temperature. It works much better if it's heated up with a hair dryer or heat gun until the piece is almost too hot to hold.
Uniformity is hard to achieve. To do the barreled action, I built a cradle that was longer than the barreled action. I took a quarter-inch aluminum rod and built it up with masking tape until it was a tight fit inside the barrel, then rotated the barreled action in the cradle like barbecue on a spit as I rubbed the bluing cream onto the action, and kept rubbing until the color was uniformly dark.
Preparation is critical. I used copious quantities of Castrol degreaser to remove any oil or grease (it was an old service rifle, with lots of nooks and crannies to hold the cosmoline), naval jelly to strip off the old blue, and then a final wash with Dawn dishwashing liquid and a hot-water rinse to get the prep chemicals off. A wire brush on a rotary tool took care of any old bluing the naval jelly didn't get.
Note that steel wool will leave oil behind, so if you're using that for prep you have to degrease again before you apply the bluing.
I'm not sure of the point of a cold-water rinse after bluing--I wouldn't do that myself. Just wipe off the last of the bluing cream, being thorough but gentle, then coat VERY liberally with gun oil (no motor oil or 3-in-1 oil) and let the finish cure for a good, long time. Two weeks is a good target, although longer isn't a bad idea. Wipe off the oil and you should be good to go.
I have to confess that when it came to the smaller parts, there were several cases where the original results looked terrible. In these cases I stripped the cold blue back off and started over.
Duracoat will last a lot longer and provide better corrosion resistance. Only you can tell whether or not it will give the appearance you want. It's a fairly permament solution, though, so be real sure it's what you want.
You may also want to think about having a gunsmith do a nice hot blue on it. With the amount of material I went through, I doubt I saved more than 50% over the cost of a hot blue.