King,
I've used electrolysis to clean pretty large engine, and car sheet metal components. A 12 volt battery charger is about right, I never used the container itself as the anode-I suspended a chunk of stainless plate, which, the the rust moved off the part and tried to adhere to. You need to add lye to the water for best results, I bought Red Devil brand at the hardware store, but, they won't sell you more than two containers a day here-the meth heads use it for something or other. Don't try to buy any other chemistry (acetone MEK, etc.) on the same trip, either.
I'm betting the process is the best bluing remover ever invented, so keep that in mind. It took about 18 hours or so to completely clean a part like an iron intake manifold, (I'm sure it was FAR nastier than the 870, rusty and gunky) and you have to rotate the part to face the anode several times-the action works best line of sight. Keep in mind it only takes an amp to kill a man, and do it in a well ventilated, but, non-exposed to kids, pets, etc. area.
Good Luck.
Best,
Ted
