Hi,
Lokidog offers sound advice.
As an alternative I'll offer what I have done in the past.
After a few failed attempts at cold bluing, (it never lasts) I bead blasted my barrel and hardware to bare metal, rubbed smooth with emery cloth, then parkerized it with a kit I ordered on line. This process is similar to the browning method lokidog references. The biggest difference is in the color obtained. Parkerizing will give a color similar to that found on military firearms.... a dull black and has much improved corrosion resistance than cold blue.
Basically, you get a cheap stainless pan large enough to hold the barrel. After de-greasing all of the parts, you bring the solution up to around 170*. Place the items in the solution. They will start to "fiz". After around 20 minutes when the "fizzing " stops remove the items and rinse them in soapy water. This stops the chemical reaction. Dry thoroughly and apply light oil.
I use a Coleman stove to heat the solution on the back porch as once the "fiz" starts there is some smell to it.
Take care,
Lee