I picked up a Knight Bighorn off Gunbroker that showed up with a rusty bore. The seller has been great about it so no complaints but now I have a project.
It’s rusty all the way to the breech plug like shown in the picture.
My plan is Kroil, JB paste, and elbow grease.

Any better ideas?

Evaporust. Plug breech, pour in and let soak. DO NOT let it get on bluing.

https://www.modernmuzzleloader.com/threads/evapo-rust-on-rusty-muzzleloader-bore.55045/#post-515234

Perfect! Looks like I can pick it up at Harbor Freight too. I’ll give it a try.
Thanks!

O'Reilly or other parts stores as well.

Saw this in the Gunsmithing forum...........

https://www.big45metalcleaner.com/

I would bore brush it good then fill with evaporust, as said do not get on bluing.. more then likely barrel is toast but if you can see rifling still will probably shoot decent just sucks to try to keep them clean and pretty much have to swab every shot as crud builds up quicker.

The most extreme rusted barrel I took on was a custom percussion gun made in San Francisco in 1858. A lot of collector value, it had a Whitworth style hexagonal bore. The owner wanted it cleaned up enough to show the rifling style and have some eye appeal. I fought it for several days, finally went on YouTube and studied the videos of electrolysis cleaning with a battery charger, washing soda solution. It did a remarkable job without displacing any metal. I used a 1/4" steel rod with nylon washers/insulators as the + anode and the barrel itself as the - cathode. I mixed the water and washing soda ....about twice as strong as recommended at 1 tsp per quart. 6 hours it was done. Changed solution every couple hours. In spite of my advice, the owner shot the thing, it's a wonder the breech plug didn't blow out the back.

Yep, the real issue is whether or not the rust got into the breech plug threads. Wouldn't be the first rusty muzzle loader to blow its breech plug.

Welcome to the Outers Foul Out. Those things flat worked and fast. Too bad they never really caught on.

Depending on the age of the Bighorn, the bore may be Dura Coated, and the rust is more residue than damage.

I’ve had three or four used Knight purchases that have cleaned up way easier than I first expected.

I start with a 20 gauge Boresnake on a .50 Knight, and go from there, depending on the condition after a couple of passes.

I have one barrel that has been cleaned of rust, but the bore surface is still somewhat lightly pitted. The rifle is accurate, but it won’t take more than one or two loads without a complete scrub of the bore, the residue builds up up much more than the others. Not unexpected, but definitely makes it non favorite at the range.

Once cleaned with Evaporust be sure to flush it water, let it dry thoroughly then apply a quality lubricant like Corrosion X. Be sure to keep the breech plug out of it during the off season. I have been surprised by some surface rust in my Huntsman barrel and doing those things have it shooting great from year to year with very minimal maintenance.

This is good advice, after the Evaporust use the Kroil, JB paste,
You'll be surprised at how clean it will be.

Thanks for all the feedback folks!
I’ll buy some supplies and let you know what the results are.

Good luck. Yeah, somewhat common fate with muzzle-loaders. I’m always Leary buying a used one without seeing it in person.

You may be really surprised after you clean it up how well it shoots. I have picked up several TC rifles extremely cheap looking just like that. I made my own electrolysis rust remover. After that I did some fine lead lapping with some diamond paste. They all shoot really well. Just have to clean them a little better than ones that have perfect bores.

Please post an after picture.

I found that bore butter and muzzleloader safe products don't do well cleaning or preventing rust. I clean my muzzleloader the same way I clean my rifles. I use Butches Bore Shine and after cleanup, follow up with breakfree (CLP) for storage (leaving the breath plug out). Before I shoot, I spray the breach plug with carb cleaner and run a dry patch through the bore, then fire a primer. I'v never had a problem loading the muzzleloader the night before opening day and it firing it 3 or 4 weeks later.

~24 hour soak with evaporust made a big difference. I’ve got penetrating oil working on the breech plug while I wait on the mail to bring bore brushes. The breech plug could be a real pain as it is the old style slotted kind and the nipple really needs to come out to get a good tool in there to turn the plug. We’ll see

Encouraging, looks much better than the first picture

The interior of my wife's MZ rusts like crazy and nothing I do stops it. Rifle is a TC Impact with the nickel/stainless finish. I remove the breech plug and clean, cover with a good oil, and put in safe. 6 months later the inside of the barrel has a coating of rust on it. No other gun in the same safe rusts. And it sits right beside my CVA. Starting to think TC might of had a bad batch of steel.
Bought a quart of the Evaporust to try.

You're not cleaning it right. After you think you're done run a quart of boiling water thru it. After it dries, plug the bbl, fill the barrel with Kroil, dump it out. store it muzzle down on an old rag. It will never rust again.

I use bore butter… well used, I haven’t shot mine in a long time

If that was the case then my CVA would be rusty as well.

cleaning with moose milk formula and finalizing and storage with a good layer of Ballistiol is your friend

Take $75 shipped for the TC?

No, if I decide to get rid of next year will find some deserving youngster and give it to them for free.

Moose milk cuts the salt, and straight balistrol cuts the sulphur.
I use simple green and water for a soap because it does not have salt like most detergents.

I let laundry soap and water sit in a barrel for an hour, it was alsmost ruined from salt. It was some Oxy brand. Anyway the cleaner could also be an issue.

plus the Ballistol is water-based and mixes with water. if you have any type of conventional water-based black powder cleaners left in your barrel and you soak it down with bliss doll it'll mix with the water when the water evaporates you will still have an oily cover. if you use something like the borebutter and you haven't got your barrel completely dry it can trap the water against the metal and therefore it can still rust.
what I call most milk anyway is 3/4 water 1/4 Ballistol plain water cuts black powder fountain quick as anything but the but mixing it with the Ballistol means it still gets oily coated when the water is evaporated.

Poor kid will have a rusty barrel!!

Looks like good progress. I'd fill it up with evaporust again. It will actually get every scrap of rust out but if when the rust is on there as thick as it was you sometimes have to dump old fluid out, scrub the part, and re-soak in evaporust. I've used it for pretty much everything.

Finding an old Knight slotted breech plug removal tool isn’t easy or cheap. Harbor Freight to the rescue. The nipple was stuck so I ground a spare chisel and worked the breech plug loose. Having soaked it for a few days in Kroil helped I’m sure.


I finally got a clear look down the barrel. It’s still not pretty after a brass brush (that’s chunks of rust stuck to the interior) so it’s back soaking in Evaporust.

I’ll keep after it and see what transpires.

I plan to order a new style breech plug and musket nipple to match my other Bighorn and for the added benefit of easier removal. Pulling that rusty breech plug was a relief!

Bore guide, rod with brush, maybe wrap with 0000 steel wool or a big patch and possibly use some JB Bore Paste and Kroil.

May be a 2 man job but chuck end of rod in drill, one person hold bore guide in place while the other runs the drill guiding the rod back and forth in bore. It may take a few cycles of this and flush with Kroil or other oil to get rid of deposits. Could do by hand but I think a drill would speed the process.

I bet it will polish up, maybe have a few pits or those may lap out, dunno.

Glad to run across this. New to muzzleloaders and bought an Impact.

Snowwolfe, I know nothing of these modern muzzle loaders, the black powder substitutes you guys use...but the key to long term storage on the old guns is swearing off of anything to do with petroleum based products. What I would do, degrease the bore with something very strong, brake cleaner, acetone, alcohol...one of those. Then wash the bore with hot soapy water. Dry it thoroughly by wiping and warming it well. While the barrel is quite warm, swab it thoroughly with a soft patch saturated in animal fat...only animal fat, not vegetable base, no mixtures, just plain animal fat/lard. Obviously avoid fats that may have salt...bacon, ham etc. If you don't have some...The easiest is just buy a pint of rendered mutton fat from Dixie Gun Works. And never again use any petroleum based product either in your bullets or cleaning regimen. There are guns today being used, almost 200 years old, well maintained with animal fats. Oil wells being scarce as the west was settled. I suppose your gun has a plastic stock, but if it had a wood stock, the animal fat is good for it. Petroleum oil softens wood. Won't cost you much to try it.

Might try Evorust and Kroil oil, then use JB bore paste to polish.

More evaporust, some foaming bore cleaner, cleaning patches, and some brass brushes and I’m satisfied with the project enough to see how it shoots. It is fairly clean just ugly.

Thanks for all the information everyone!

The Evaporust was new to me and quite a game changer. I picked up some of the Big 45 Frontier metal cleaner for the exterior rust and I am impressed again.

An oldtime smokepole mechanic would "freshen up" the bore, using a single tool steel cutter that follows the grooves one at a time- - - -deepening the groove a thoudsandth or so at a time by putting shim stock under the cutting tool. It's been done that way for a couple of centuries.

Time for a polish with a slurry of Kroil and JB Bore compound.