I bought my parkerizing chemicals from Shootersolutions.com. Like bruski said, I blasted the parts with aluminum oxide, cleaned them real good with acetone, and dropped them in the solution at 190 degrees F. until they stopped bubbling, a quick rinse in hot water, and then I rubbed them down with cosmoline. I used an old stainless pot on my stove, but I have a poaching pan and a two burner hotplate to do the barrels with. Brownwlls sells the chemicals also, and they have an online tutorial.
As far as the brass goes, I don\'t put anything on it. Once the gun is complete I\'ll just let it age to a nice patina.