I'm not saying this is the best way as I've never done it before, but this is what I did and it worked for me :grin:
First up end the bore and empty out the loose stuff...
The bore will now look something like this...
Clean it out with a rotary wire brush on a long shaft, this is a 4" brush going down a 3.6" pipe...
It will now look like this. Extract the ball as best you can and then brush to the bottom...
A pressure washer will fetch out the stuff you loosen up. Mine is only 18" long an extension to reach the bottom end would be neat. Wear old clothes...
Put in your sacrificial iron anode, you want as much surface area as you can get and it must go all the way to the bottom. I'm using bits cut off a plastic bottle to stop it contacting the bore. Don't wrap it too well because it tends to remove rust only where it can "see" the anode. Connect the anode to the positive side of your battery charger, connect the negative to the cannon. Include an automotive bulb in the circuit, the bulb should come on only if you deliberately short the anode to the cannon...
Add electrolyte and the bulb will come on. I'm using washing soda, a large handfull to a bucket of water, the concentration is not critical. Leave it to electrolyse for at least a day. Red guck will float to the surface. The bubbles are a washing up liquid pollution, if your anode makes bubbles you are pushing too much current, smaller bulb required. If you use a hydraulic hoist don't rely on it overnight, add rope and make sure the cannon stays upright if the hoist fails. The electrolyte will go everywhere and I have a few new dents in the garage floor...
You'll need to empty it out, brush and wash out the black iron residue (black because you are reverting the rust to the original iron) once a day until you see metallic iron. Clean the anode with that pressure washer while you're at it. If there are any large lumps of stubborn rust down the bore, put and iron bar up against them and hit it with a hammer until they surrender. I eventually cleaned the bore with washing up liquid, brushed and pressure washed and here it is, rust free iron. You can just make out the constricted powder chamber and hemispherical bottom end...
I really wanted to get some rust preventer in at this point. I've ordered wax oil but it hasn't arrived in time, so I may need to do this one again for an hour or so.
best regards
Squire Robin
