I have decided to try electrolysis to remove and loosen the crap. 

My local armoury gifted me a solution for the process. So I will set up a DIY rig and see how it goes. 

One point that seems odd to me; having looked at several examples of this method on the net. Most say use the "positive" on the barrel and negative on the cleaning rod. But my brain is telling me that current flow is from negative to positive, so I would expect it to be negative to barrel, positive to the rod. 

Anyone actually used this method sucessfully ?

 I think the direction of current flow depends on if it’s “charging” with a battery hooked up, or if it’s “discharging” with a load hooked up. I think the rod would be the cathode with the negative connection.  If you reversed the connections, it might erode the rod.  There were two solutions, one for removing copper and the other for removing lead. Powder fouling has to be removed first, or it won’t work. The rod must be periodically removed, cleaned off, degreased, and refill with new solution. 

I use it regularly on anything rusty that needs a good clean.  Most recently, I used it on a 6Lb AP projectile.  The part being cleaned will turn black (or at least a dark grey) and will rust very quickly afterwards, so will need to be oiled quickly.  I would try with a test piece to see if you are happy with the result.  to do the inside of a barrel, you will need a non-conductive stopper at each end, to ensure the anode and cathode do not touch.  If your voltage source has an ammeter on it, watch and see when the current draw drops.  Once this happens, run under hot water to flush out all the crud and scrub with a brush.  Rinse and repeat, as they say.

I may test the system on a short piece of rust steel pipe; just to confirm the polarity effect and solution strength etc. 

I made a power source using a 15 volt 0.5amp charger from a LED inspection lamp. It should work quickly with this voltage.

Hopefully get chance to test it at the weekend; depending on the Honey- do list! 

IIRC the electrolysis works by changing the electron sheIIs in the material to be removed, adding or subtracting one from the outer sheII depending on what material it is?

If I'm right it's quite possible its electron stripping intentionally?

Anyway, I appreciate the help. I'll post details when I get it done.

Currently busy with decorating as well so time is a premium at the moment!

Here is a trigger assembly from a MH rifle that had been converted to 303, only to have someone discard it in the desert when a she!! casing got stuck.  At some point it has been driven over and has two bends in the barrel.  I have disassembled the action and slowly running the parts through the electrolysis tank to clean them up.  The trigger isn't freed up yet but I have gotten enough rust off the block to now see the retaining screw for the firing pin.  The rifle and action body has been sectioned and I plan to section the block once I can get the firing pin out.  It should make a nice wall hanger once done.

Regarding the charger; the one I have does show voltage at the clips when testing with a volt meter. However I will check with it connected. I do have an older style 12 car battery charger if needed.

A trip to the hardware store this morning!

I have provided what I use for rust removal and what works for me but I am mindful of what I use it on, as it does leave the piece black, as shown in my pictures.  I have never attempted my method on a barrel, which is why I recommended using a test piece.

The solution starts fizzing immediately when the current is on. It slows after 10-12 minutes. I carried out two 12 minute sessions on this piece.

This was connected Negative to the rusty pipe and Positive to the clean rod. 

The solution turned rusty brown and the pipe is definitely cleaner. 

But I will test with Sodium carbonate. 

Regarding the different polarity mentioned in the various techniques; could it be due to what we are trying to remove? Would Copper removal require the opposite polarity to rust?

I will post some pics, but can't do it from my phone ! Files are too big.

I would be cautious Shaun, last thing you want to do is pit the barrel.  If it were me, I’d use JB. 

 I have not tried it yet. The Armourer also gave me a bottle of "Cop Out" and suggested the electrolysis. He showed me some bore scope images of a 30.06 that he had used this method on. 

I showed him the bore image of the Maltby. He thought it could be effective. 

This rifle was stored for around 70 years. I will continue testing the method before making a final decision. 

The articles I've checked say (for rust removal), However copper may be different because of the structure. Different anodes cathodes chemical solutions & metals will all have their own particular setup.

"

1. Attach the positive (red) clip of the battery charger or power source to the rusted object, making sure it has direct contact with the rusty area.
2. Attach the negative (black) clip of the battery charger or power source to the sacrificial electrode. The electrode should be immersed in the electrolyte solution but not touching the rusted object.
3. https://removemania.com/how-to-remove-rust-with-electrolysis/" rel="nofollow - https://removemania.com/how-to-remove-rust-with-electrolysis/
   

However, I agree with Britrifles words of caution regarding damaging the barrel.  Whilst I have not seen evidence of anything other than rust being removed (i.e., no damage to non-rusted material), I really only use this method on things that are manky to begin with.  My primary concern was the blackening of the base metal where the rust has been removed, as shown in the pictures shown in my previous posts.  This is why I suggest testings some pieces first.  My other concern was placing the anode inside the barrel without shorting it. 

I tested using the negative on the rusted object; but I was using a different solution (ammonia, white vinegar and water). Two 12 minute sessions of 15 volts at 0.5 amp max.

Here's the test piece.

First results, obvious reduction of surface rust on the test piece (left). But could be better; possible with extra sessions.

I will do some more testing with Sodium Carbonate soon. (I will make my own from Sodium bicarbonate)

I think you have the right idea with so much conflicting info.

IIRC its a slow process, so try overnight maybe?

For test you might want to "go over" just to check it doesn't start eating the steel as well as the rust.

Ideally you'd like it to eat all the oxide, but none of the metal.

I will test with Sodium carbonate. 

I will be doing more tests before attempting to clean the barrel.

Just my 2C`s  worth of wizzdom, I`d be Leary about electro eroding the barrel and what I`ve done with a few rusty bores is to fill them with vinegar, plug the breech fill, let sit over night. empty scrub, repeat as needed. Use 5% vinegar as its less aggressive but works just fine.

In some case it will ever start to resolve copper fouling. 

Vinegar is an acid, a weak one, but still acidic.  Ammonia is a weak base, so these two perhaps cancel each other out to some degree and may not pit the barrel if not left in too long.  Ammonia will certainly attack the copper that is in there.   

Perhaps give it a good soak in Kroil for a few days and brush with a bronze brush.  I bet that takes out all the rust. 

Two 15 minute sessions. The positive rod requires cleaning after 15 minutes, due to the build up of rust on the positive steel rod. Wipe out the tube with a rag between sessions. 

Still, would make me nervous doing this on a barrel. Unless you plan on changing it regardless and just want to experiment. 

The black coloration is very common with rust removal chemistry to varying degrees. The process, called "Chelation" draws carbon from inside the steel's structure to the surface as part of it. It can vary from mild grey to jet black.

All the gruesome details:

https://en.wikipedia.org/wiki/Chelation" rel="nofollow - https://en.wikipedia.org/wiki/Chelation

So after considering the various possible outcomes; I decided to treat the barrel.

I used the Sodium carbonate with one 13 minute cycle. The barrel had not been fired since the last normal clean.

4mm bar stock is used for the Positive; insulated with small "O"rings. Plugged the muzzle with a cork and filled the barrel with the sodium carbonate solution. 13 minutes of electrolyisis; white foam forms almost immediately, turning brown toward the end of the cycle.

Obviously the amount of liquid is small in the barrel with the 4mm rod. Draining shows very dirty solution with particles.

 I then flushed with a litre of boiling water; using a homemade funnel.

Then I carried penetrating oil wipe through. Then the addition of a scrub with Bore Tech Chameleon Gel;(first time using this); before continuing with the normal clean.

Unfortunately I didn't have the borescope available this weekend (no laptop). But to the naked eye, the bore definitely looks cleaner, bright and shiny. 

I will inspect with the borescope next weekend to compare.

My thought based on the image looking down into the breech from the magazine well, is that you slightly over-filled it? Not easy to d I know.

I wouldn't mention it except to ask if it was past the level where the barrel & receiver threads end.

I'm concerned with the solution wicking down int the threads possibly causing problems later?

After you shoot it, use a good copper cleaner for the next few times you shoot.

I wicked off the excess foam and liquid after taking the photo. 

First photo is how it looked when I first got the rifle.

Next is after multiple ordinary cleaning after shooting several times. Not sure of the round count, but probably between 100 and 150 rounds.

Finally, after one 13 minute electrolysis, hot water flush and clean, using C4 carbon remover and a kroil type product. The barrel is still frosty; but does show some improvement. A lot of carbon was removed when cleaning. I will use JB Paste to polish the surface. 

The rifle does shoot quite well; within standard spec'.

What does the throat look like? Particularly in regards to firecracking. You may not be able to see it without a mirror though. 

Here is the start of the rifling. I don't think this rifle has bad much use. Evidently, I need to invest in a better scope. But I don't see any obvious signs of cracking.