Experts please advise: inexplicable barrel fouling - affecting accuracy - "lumps" in lands

[zambezi]

Load development for all my rifles has proceeded very well. In all but one case I have created ammunition that out performs any off-the-shelf offering.

The exception is my 6.5x55mm.

So I quit development for that caliber and went back to factory loads only to discover that those groups aren't as tight as they were prior to development testing!

I cleaned the barrel using the method I have always used on all my rifles, tried again. Factory performance still lacklustre. I.e. factory ammo that delivered sub moa prior to load development, is now more like 1.5 moa.

So I bought a borescope and it has been a revelation. More like Nighmare on Elm Street really.

HEAVY copper fouling that KG12 and brushwork aren't shifting, and what looks like carbon nuggets embeded in the lands half way up the barrel. Why I say "embedded" is because there is reduced/no copper fouling on the lands after the lumps. I.e. on the side of the lump nearest the muzzle.

This lumpy deposition is unique to this rifle. I have inserted the borescope onto three other rifles tonight and they look factory-fresh. For example this image of my much higher round count 30.06: I cannot stress this enough: all rifles are cleaned the same way.


So my questions to the experts would be: (1) what is the likely cause? (2) Is there any obvious fix?

 

[ashray]

are you using non lead bullets?

 

[Yorric]

It looks like galling of a heavy copper fouling build up with something embedded in it.
That copper needs removing and the best way I know to clean that out is by using Kg2 bore polish on a tight four by two covered jag.
I'd then use HBN coated bullets and swab the bore with it in alcohol to avoid a repeat of the copper fouling.
Ian

 

[Chris J]

I'm guessing this is not a stainless barrel. I don't think any amount of cleaning is going to fix pitting like that. Happy to be called wrong, but I think the only remedy for that is a new barrel.

 

[Heym SR20]

If its pitting, its likely to be powder residue attracting moisture - its why i like to run a patch lightly oiled down the bore after shooting. I don’t leaving powder residue in a barrel if the gun is not going to used the following day.

Doubt it will affect how the rifle shots.

 

[Bowland blades]

I'm guessing this is not a stainless barrel. I don't think any amount of cleaning is going to fix pitting like that. Happy to be called wrong, but I think the only remedy for that is a new barrel.

The stainless used in rifle barrels will not prevent genral rusting fully , certainly won't that kind of corrosion which is generally caused my moisture under copper fouling . Many overestimate what magnetic stainless steels can achieve on preventing corrosion unfortunately

 

[Bowland blades]

Anyhow I have seen worse that still shoot ! You might have to get a few fouling rounds down it first or it might shoot best as clean as possible, contradiction? yes ! But thats how it goes .
Unfortunately it will now mess with your head

 

[hammo]

Borescopes are the work of the Devil himself.
A handy tool if you are inspecting a Rifle prior to purchase, BUT look down your own barrel and you cannot un-see things like this.
Best of luck, not helpful I know but there it is.

 

[8x57]

Normally I would tend to agree with you Hammo but in this instance it may be different. Are the black bits flecks of embedded carbon or are they rust?
C2R is one of the most effective bore cleaners that I have used. It's a combined carbon and copper remover. I would give that a try and see if that makes any difference.

 

[Jelen]

OMG, I'm not buying a borescope. Ignorance is bliss.
Sorry that doesn't help you, but that looks more like pitting than build up? If it is pitting, how old is the barrel?
It could be a bad barrel from the outset? I bought a 6.5x55 barrel for a Blaser I owned when they first came out. It was the worst barrel I ever owned!
I only had to show it a cartridge and it would copper up. It was a pain to clean. No matter how I cleaned it the patch would judder up it. Never got a smooth stroke of the rod through it.
Sold it in disgust!

 

[Dalua]

I must declare that I am no expert at this - but I do own and use a borescope, and I have rifles with barrels ranging from clean as a whistle to rougher than a bear's bottom.

I think the monocular view can be perplexing, and therefore I wonder whether the pictures are showing pitting, rather than 'lumps'?

 

[Yorric]

The way to know if they are lumps or craters is to polish the bore. Then when clean the important thing is to stop copper & carbon building up again. -- See my earlier post.-- The HBN coated bullets & bore reduce fouling & lower breach pressures by imparting a lubrication layer between steel bore & bullet material.

Ian

 

[cjm1066]

I have a 1950s BSA, using a bore scope it looks horriable, it stil shoots.

I use Forest Foam and often leave it for hours or overnight - none of my rifles have copper in them.

 

[zambezi]

I bought a 6.5x55 barrel for a Blaser I owned when they first came out. It was the worst barrel I ever owned!
I only had to show it a cartridge and it would copper up. It was a pain to clean. No matter how I cleaned it the patch would judder up it. Never got a smooth stroke of the rod through it.

I have three Blaser barrels, bought within a year of each other. The other two do not copper up like this. Like you, I wonder if I got a duff 'un.

Forest Foam and often leave it for hours or overnight - none of my rifles have copper in them.

Until now I have resisted overnight soaking of barrels and limited chemical contact time per the manufacturer. But I think this barrel is going to get an overnight steeping in Forrest Foam. And maybe C2R next.

I wonder whether the pictures are showing pitting, rather than 'lumps'?

Still images do not show the whole story. As you move the business end of the borescope, the light source embedded in the tip of the fibre traverses the bad sections like the arc of the sun across the land. And like the sun, you see the shadows of objects switch from forward of the light to rearward once you pass over. I am pretty sure these are lumps, not pits. I.e. whilst the central image is a "plan" view of the lands, the camera is simultaneously filming the bore radially/longitudinally. That side view corroborates the plan view diagnosis that I am looking at lumps . The arrows show direction of camera travel.

I have seen worse that still shoot !

If grouping was satisfactory, I would never have taken a look with the borescope. Inability to make reloads or factory ammo group well forced my hand.

but I think the only remedy for that is a new barrel.

Blessedly, my wife heard me groaning as I looked at the PC screen and came into the study to look over my shoulder at the images. First thing she said was "it looks like you need to buy a new barrel". Did I mention she is a keeper?

 

[Steff]

The Forest foam won't help you on this; it's much to weak. TBH I am very surprised that the lands are still coppered up to such an extent after you have used KG12 on them.
Buy some bore paste (JB's, VFG or any other) and really get the barrel clean. My guess is that once the lumps are gone there'll be pitting underneath them. I consider the lumps to be rust bloom.
Do you get or did you have any brownish discoloration of your patches?

 

[Yorric]

Before spending money, do give the bore a Kg2 (not KG12) polish on a tight patch. Scrub it firmly. You can add a drop of light oil to aid the cleaning action.
Badly fouled bores are usually brought back to a high shine in a few minutes.
Note I'm not advocating using Kg2 for everyday cleaning. I use it just for this type of occasion where normal cleaning hasn't done the job.
I finish the bores by mopping out with oil to wash off any Kg2 before applying the HBN.
Ian

 

[takbok]

JB bore compound or similar might be worth a try.

 

[bullet chucker]

CALM DOWN AND CARRY ON'
Clean your barrel with chemical as said above check the results shoot for groups then decide from there.

BC.

 

[gixer1]

What brand of rifle/barrel?

 

[Chris J]

Didn't the OP make the point, expressly, that accuracy had gone off?