I have an old worn out 870 that needs to be refurbished.  I'm thinking rust blue looks like the most attractive option.  I have a spare barrel, so I don't need to refinish it.  The gun is in good working order, it just needs to be cleaned up and refinished.

Does anybody have much experience?  The receiver was rusted at one point, but a previous owner removed most of it from the outside, but not inside.  The outside may have some minor imperfections to buff out, I'm not sure yet.  It seems to be mostly imperfections in the finish.

My main concern is the inside of the receiver, and I guess the mag tube.  There's some rust inside the receiver, so I wasn't sure if I should just soak it all in vinegar first and clean it up, or if I need to strip the finish out of the inside as well.

I'm also not sure if I need to remove the ejector.  I hope I don't need to do anything with it.  I'd like to just refinish the outside if that's a good route.

I guess my main uncertainty is the best way to get the metal prepped and any 870 specific concerns, mostly about how far to tear down the receiver and if I need to refinish the inside as well.  I was also thinking about finding a big cheap aluminum pot and something to boil water outside, since the receiver is relatively small, but I've read pouring a bunch of boiling hot water over the receiver in a sink would work as well, so I haven't decided what the best option is.

The old barrel is rusted pretty bad inside, so I was planning on cutting it to practice cutting for the good barrel and using the pieces of the bad barrel to test the rust blue process.

Tag for info

Honestly the easiest one to use is Laurel Mountain Forge Browning/Blueing  



Basically strip and degrease for prep.  simple directions
Unless you really want it to shine, then LOTS and LOTS of polishing. I would definitely disassemble all or as much as I could of the receiver.
and don't try to blue any areas that you can't reach easily to card. Anywhere you can easily fit a toothbrush is OK though.

No need for boiling the parts after each rusting cycle. Scalding (pouring boiling destilled water over the part) is all it takes.
I built a 'scalding trough' from 6" PVC pipe and endcaps, cutting a little over 1/3 off of the pipe the entire length, an gluing
the endcaps on.

If you can't rig a 'rusting cabinet' , hang the parts on a towel rack in your bathroom outside the shower and run it on hot
to steam the place out.... The wife loves that

It's really not hard, just time consuming

Here's a few pics of some of the stuff I've done (Note, I don't really polish these, I dig the nice charcoal satiny look) these have anywhere form
4-6 rusting cycles to achieve good colour

Husqvarna 1907 Slide (before, during, and after)



An old, beat to hell Savage 1907 (note I didn't polish this just blued)



The receiver on an old 1899 Takedown (before it looked as grey as the stock ferrule)



And an old Savage 620 12ga barrel

Rust blueing isn't hard at all.

I test blued a Remington 700 recoil lug, and it came out good.

You cause the part to rust by whatever means. This means a salt or acid solution of some kind. Anything that's going to cause the steel to rust when you expose it to the acid will do. Battery acid, bleach, hydrochloric acid will all work.

Place the part somewhere very humid (hence a sweat cabinet) for a few hours and the part should rust.

Boil the rusted part in distilled water (or scald it, if it works) and the rust turns black.

Wire brush the black rust off, and repeat until you get the colors you want.

I plan on doing a receiver at some point... those cold blue sucks and never seems to come out right.

Disassembly is my main concern. 870s are easy, except the ejector.

Your guns look really good.

If it is not perfectly degreased, you will have imperfections. That would be my only issue with an incomplete disassembly. I had issues with grease used on barrel threads leaching out and causing issues.

If you can knock down the rust with steel wool, then boil, it will convert the rust to blue.

It isn't a difficult process. The only issue is getting tanks big enough to hold the parts.

You don't need boil to convert the rust.  A homemade PVC steamer (vertically oriented) works just as well, and it can pull double duty in the woodshop.

I achieved a very good finish on a barrel using the Laurel Mountain solution, but there was a lot of trial and error. I made a steam pipe, but somehow had condensation problems. I ended up using a very large roasting pan on the stove and it worked great. I diluted the solution 50/50 with distilled water after the first couple of passes because I ended up with small pitting on my first attempt. I also oiled the black velvet after it came off the boil and let it sit overnight. The stuff wiped off easily the next day with a paper towel and I quit using steel wool and my carding brush altogether. It took more degreasing that way, but it looked better quicker to me, compared to my first try. YMMV, but that's what worked for me. Finally, check the finish out in sunlight. You will see flaws that inside lights won't reveal. I thought mine was done until I took it outside and it looked like a splotchy  mess. A few more passes and it looked flawless.

OP,
Did you ever try the process out, and if so, how did it go?  I would like to try this on a surplus Star BM that I just purchased.  Anyone else have pictures of their DIY rust bluing?

bump

I've done a bunch of muzzle loaders and even did a Saiga I converted about 5 years ago. You can only successfully rust-blue parts you can reach to card off the rust.

Use metal guttering. Cut to length and either solder on the end caps or glurle them on with epoxy. When filled with water and boiled across a few burners on the stove top, the water will prevent melting of epoxy or solder.

Bump