Copper-collecting barrel

[High Plains]

A friend sank a lot of money into a high-dollar rifle. It can make 1/2” size shot groups at 100 yards, however, the button-cut barrel fouls quickly. Much time has been spent removing copper from the barrel after the group opens, only to have the groups return to well under an inch after a lot of cleaning time, then after about 20 shots it is back to big groups. All-copper bullets and standard cup and core bullets from Sierra and Hornady foul up the barrel equally.
He sent the rifle back to the manufacturer, fouled barrel and all and the response at first was “you have a really dirty barrel” and the next one was “it groups very well after removing the copper.” He knew these things but wanted the company to see what the fouling was like.
I told him I think the barrel has a lot of rough spots from the button cutter. A gunsmith said there are likely a lot of machining marks in the barrel.
I see three options for here. If he takes it to Africa in the Summer of 2022, as he wants to, he has time to have it rebarreled. More $$ into a pricey rifle isn’t too cool. He could also take it squeaky clean, when he knows the accuracy is there, and clean it when he is there for continuing the desired accuracy. He can also switch to a powder like RL-26 or IMR-7977 to take advantage of their anti-copper ability.
If ya’ll have ideas on a solution for him, please post it. I told him RL-26 nearly eliminates copper build up in my 7mm Weatherby and I’ve put a lot of all copper bullets down that barrel.

 

[Steve S.]

I have a copper eater myself; the accuracy does not deteriorate as quickly as your friend’s rifle but, I can see lots of copper residue after about five shots. My rifle is also a shooter with reloads so I have kept it.
I have chosen to live with the copper because of the accuracy and clean it with Boretech Eliminator (it melts the copper quickly “like butta”), no muscle involved. It is the trade-off choice that I made, he may choose another.

 

[edwardware]

I'd clean it.

I might also clean it sooner each cycle, as the most effective break-in is the first shots over a clean bore.

I would also handlap it, and consider firelapping, to smooth it out.

But I would keep it, shoot it, and clean it, for sure.

 

[denton]

I think the following theory and method is the correct way to deal with a barrel that fouls excessively:

When a bullet encounters an imperfection in the barrel, it leaves a little bit of itself behind. That makes the imperfection bigger. The next bullet then adds to the pile. Only the first bullet down a completely de-coppered barrel tends to smooth the imperfections, and subesequent bullets do not.

So the recipe is to carefully de-copper the barrel, and then clean after each round for about 30 rounds. Then de-copper after 3 rounds, for an additional 30 rounds.

I have a Swedish Mauser, over 100 years old, that got that treatment. It went from fouling badly to barely fouling at all.

 

[Walkalong]

And then buy another brand barrel when it's time.

 

[Bfh_auto]

Mother's mag polish on a bore snake about 20 times helped on my copper eaters.
After that I dry patched then until the patch came out white.
It was tedious work. But it paid off.

 

[High Plains]

A top-notch tinkerer mentioned Tubb’s lapping system to smooth the barrel. I’ll mention it to him. As far as I know, the lapping is going to smooth the rough spots without increasing the ordinary wear on the barrel.

 

[243winxb]

http://www.davidtubb.com/final-finish-bullet-kits A shooter at my club was shooting a 338 Lapua in a Savage rifle. He said the target & bore scope showed improvement after use.

 

[Ru4real]

I lap my barrels by hand. I used a carbon fiber cleaning rod, a brass cleaning jag, cloth and Wheeler Engineering 320 grit and 600 grit lapping compound.

The idea is the same as removing machine marks from a flat surface with lapping compound. In the bore, the cloth laden lapping compound is pinched between the brass jag and the bore. The tighter the fit the better. The cloth I prefer is cut up old bed sheets because of their strength and ability to hold the lapping compound.

Clean the bore first really well. Then begin lapping. I use about 10 patches and spend an hour polishing the bore.

I just did a Savage 223 last week. Before lapping, accuracy went south after about 100 rounds and it took brushes and solvent to clean the bore. I put about 100 rounds through the polished bore a couple days ago and accuracy was still good. Yesterday I cleaned the bore, no brush. The third patch came out clean, and I was done cleaning the bore in 2 min.

 

[stillquietvoice]

Fire lapping, cleaning after every shot or hand lapping will likely be the best bets. If his barrel is real accurate and the manufacturer replaces it it may not be as accurate as his current one.

 

[Walkalong]

A true match barrel doesn't need any work from the shooter, they do it for you. Since the OP said "a high-dollar rifle" I am assuming a "match" barrel. It should not have this issue.

That said. This is the bore from "a high dollar rifle" (2K) bore I had. Unacceptable at that price range..

 

[denton]

I strongly recommend against firelapping. It is basically adding serious wear to the barrel. You can get the needed results without anything so drastic.

 

[High Plains]

A true match barrel doesn't need any work from the shooter, they do it for you. Since the OP said "a high-dollar rifle" I am assuming a "match" barrel. It should not have this issue.

That said. This is the bore from "a high dollar rifle" (2K) bore I had. Unacceptable at that price range..
View attachment 994641

I think it is machine marks like these causing the speedy copper build up.

 

[Ru4real]

I agree, match barrels shouldn’t need any lapping. I have two Krieger and one ER Shaw match rifle barrels and they are mirror smooth. I have several hand gun barrels that are also match grade and mirror smooth.

The results of the Tubbs fire lapping process are hard to argue against.

And obviously I believe in the results from my hand lapping method, or I would have quit after the first rifle.

If you believe that copper or copper alloy will quickly wear down the machining marks left from a poor rifling process, then you should probably do a hardness comparison between copper alloy and chrome moly steel or stainless steel.

Depending on the severity of the roughness, it could take decades of regular shooting before a barrel comes into its own.

 

[Ru4real]

View attachment 994641

Outstanding photo @Walkalong! This photo is typical of a factory bore from Savage, Winchester, Ruger, etc. Suppose it is a 7mm bore.

The barrel is first drilled at 0.277” and those are the rough machine marks we see in the photo. Then a button or similar is pulled through the bore, squishing down part of the bore to 0.284”. You can still see the faint machine marks in the bottom of the 0.284 bore, but the button did a pretty good job of smoothing them out (reflecting lots of light).

Fire lapping or hand lapping is the final step to smooth out and polish the 0.277” land, the part the button never touched. The 0.284” grove is polished just a little, not very much in the lapping process.

It’s easy to see and identify the lands in a dirty bore because they are copper colored and the groves are black. Looking at @Walkalong photo, it’s easy to understand why the cheese grater land is collecting the copper.

 

[TEXASJD]

A friend sank a lot of money into a high-dollar rifle. It can make 1/2” size shot groups at 100 yards, however, the button-cut barrel fouls quickly. Much time has been spent removing copper from the barrel after the group opens, only to have the groups return to well under an inch after a lot of cleaning time, then after about 20 shots it is back to big groups. All-copper bullets and standard cup and core bullets from Sierra and Hornady foul up the barrel equally.
He sent the rifle back to the manufacturer, fouled barrel and all and the response at first was “you have a really dirty barrel” and the next one was “it groups very well after removing the copper.” He knew these things but wanted the company to see what the fouling was like.
I told him I think the barrel has a lot of rough spots from the button cutter. A gunsmith said there are likely a lot of machining marks in the barrel.
I see three options for here. If he takes it to Africa in the Summer of 2022, as he wants to, he has time to have it rebarreled. More $$ into a pricey rifle isn’t too cool. He could also take it squeaky clean, when he knows the accuracy is there, and clean it when he is there for continuing the desired accuracy. He can also switch to a powder like RL-26 or IMR-7977 to take advantage of their anti-copper ability.
If ya’ll have ideas on a solution for him, please post it. I told him RL-26 nearly eliminates copper build up in my 7mm Weatherby and I’ve put a lot of all copper bullets down that barrel.

First I would hand lap it with J&B compound, If he reloads I would Molly the bullets this will cut down on copper fowling. Its strange for a match barrel to copper foul that fast but the patch and rod J&B will take care of those tooling marks. Most high end barrels (Lilja Shilen..) are already hand lapped.

 

[Walkalong]

lap it with J&B

That pic is after I cleaned it out with JB.

 

[TEXASJD]

That pic is after I cleaned it out with JB.

That's bad

 

[High Plains]

UPDATE—— the owner of the rifle with the fouling problem said a bore scope relieved a lot of fissures in the barrel nearest the breech. I’m guessing there was an imperfection in the metal that caused it. The rest of the barrel is very good. Loads with RL-16 have shown considerably less copper build up, so I think he’s on his way to more time between copper removal sessions.