I've had decent results with home brew on a couple Norincos. 1 bottle of rust converter from Canadian Tire, 3 liters distilled water, toss in a degreased steel wool pad and heat. When the steel wool is mostly dissolved I pull it out and drop the gun parts in to the solution to cook for a while. I use acetone or brake clean to degrease after bead blasting. I have a very understanding wife, but I don't think I'll parkerize anything on the kitchen stove again. I've only done handguns, so I bought a cheap stainless mixing bowl with a flat bottom.
This one turned out a bit splotchy. I added manganese to the solution and had a lot of sediment piling up on the horizontal surfaces. I will probably redo it in the same solution I used for the one with the comp, it turned out much nicer without the manganese.

Kristian