MAJOR Copper Fouling - Why?

[FeMan]

I am putting together a 300 PRC for a friend. I had the barrel chambered. I scoped the barrel (Bartlien 9 twist 5R). It looked beautiful. I cleaned out the oil from the barrel and seasoned the bore with colloidal graphite, loaded up some mild loads with 212 ELDXs at 20k off (77 grains H1000) and headed to the range.

After just one shot, I could not believe the copper on the patches and could not get it all out. I must have run 25 patches with Boretech Copper and it was still very green/blue. Since I didnt have my borescope and am impatient, I decided to rinse and dry the bore and shot four more to get it zeroed.

When I go home I bore scoped it. The last nine inches of the barrel had deep, thick deposits of copper in the grooves. Probably 25% of the cumulative grove length in that region had THICK copper accumulated in them. I have broken in 50+ barrels this way and never seen anything close to this.

After 5 1/2 hours of cleaning, I am down to my last small patch of copper in one grove near the muzzle. When that is gone, my plan is to rinse the bore and take her out and fire one shot and re-examine.

I have no idea why/how this happened and am hoping the nightmare is over. We shall see I suppose. I know copper has an affinity for itself, so maybe once it is all 100% gone it will be smooth(er) sailing.

If anyone has any thoughts or insights into what/why I would appreciate them. Thanks!

 

[ebb]

Wouldn't Bartlein be the people to ask?

 

[butchlambert]

Did you break in the throat before firing? If not, do a search on the forum about this.

 

[Dusty Stevens]

Did you scope it before you shot it?

 

[tobnpr]

I would think something's gotta be stripping that copper.
When the copper was removed, you saw no evidence of tooling marks from the rifling cutter in the grooves?

 

[SKWERLZ]

Copper getting hammered at the throat area then accumulating when pressure (and heat?) dies off a bit.

 

[moondog]

Both my 2 300PRC barrels copper horrible in the same area during break in. I do the Colloidial treatment too.. Borescoped, the barrel look perfect. Last one Bartlein, this one Brux. 18 shots later, and done. Now, I can shoot 120 rounds with zero copper.

 

[FeMan]

Thanks for the replays. I called Bartlien, Forgot to mention that. They are an obvious one to ask. They didn't answer the phone but I left a message. I'll talk this through with them when they call back but I thought I would ask this group in case they had some insight to add.

Yes, I scoped before firing and everything - barrel, chamber and throat - looked absolutely perfect. After cleaning, the bore looked like before - perfect with no defects or unusual tooling marks observed anywhere.

 

[SKWERLZ]

I learning to love colloidal graphite but I don’t use it on initial seasoning of the barrel
I want that throat sorted out ASAP
It’s wonderful after some barrel wear as it really seems to minimize the effects of cleaning vs lightly fouled.

On some barrels cold bore clean barrels shots are no different especially as I clean more frequently now than in the past to limit total fouling.

Still testing it but I like what I see.

 

[FeMan]

I learning to love colloidal graphite but I don’t use it on initial seasoning of the barrel
I want that throat sorted out ASAP
It’s wonderful after some barrel wear as it really seems to minimize the effects of cleaning vs lightly fouled.

On some barrels cold bore clean barrels shots are no different especially as I clean more frequently now than in the past to limit total fouling.

Still testing it but I like what I see.

I am thinking I will wait until I can confirm no copper from now on. I typically get zero copper or very very little initially. This was an eye opener!

I got her clean and ISSO'ed the throat. Will shoot one and look tomorrow and report results.

 

[Carl S]

Sound's really bad,especially for a match grade barrel of that quality.they are normally very good.maybe your reamer has left a raised burr in the throat.

 

[DR_2297]

This is an interesting topic. I have a fresh Bartlein 7.5 twist in 6XC that just did the same thing on its first outing with 108s and a mild charge of H4350. Not as bad as this but the condition is the same. Last few inches had a lot of copper to the muzzle. Rest of the barrel nada. It’s cleaned up now and in will drive it @ Camp Perry Sunday and see how it looks after about 70 shots.

 

[Drop Port]

Had a Hart barrel do the same thing in the last few inches, shoot and scrub, finally went away and was a great barrel. Never figured it out just assumed an inconsistent lap job.

 

[L.Sherm]

In my experience what happens like the O.P describes wether its last few inches or alot its the throat nothing to do with the barrel itself.

 

[Dusty Stevens]

If the copper is at the muzzle end its 99% an issue with the throat. Itll usually sort itself out which is what barrel “break in” does but not always

 

[ebb]

My friend that got me shooting long range had a match barrel that took 100 rounds till it stopped coppering. It was a brand that has as good a reputation as yours. It always shot super groups, before and after it stopped coppering the barrel.

 

[FeMan]

I shot one shot today and have a ton of copper. Enough to take 6 or 8 hours and as many ounces of copper remover and scrubbing to get out.

The comments about the throat make sense. Thanks for those. I did compare this barrel to a half dozen I have chambered and ready to go. The one thing that stands out in comparison is that the rifling looks very rough in this one, almost like it skipped or got short changed in the lapping process. Could rough land and grooves be a possibility as well?

 

[L.Sherm]

If the lands and grooves look rough it certainly can but I'm confused now, in your original post you mentioned it looked beautiful.

 

[FeMan]

If the lands and grooves look rough it certainly can but I'm confused now, in your original post you mentioned it looked beautiful.

Sorry of I confused you and others. What I meant was, to me it looked beautiful. I have looked chambers and barrels before but am not expert. I was checking for obvious tooling mark, voids, etc.

Today, it occurred to me to look more closely and and so I looked at this one side-by-side with others. The striations are definitely is a lot rougher than any of the other barrels waiting in the que.

 

[SKWERLZ]

Sorry of I confused you and others. What I meant was, to me it looked beautiful. I have looked chambers and barrels before but am not expert. I was checking for obvious tooling mark, voids, etc.

Today, it occurred to me to look more closely and and so I looked at this one side-by-side with others. The striations are definitely is a lot rougher than any of the other barrels waiting in the que.

It may look beautiful but under high magnification it’s swathes of sharks teeth and it needs 50-100 mike Tyson punches (shots) to knock those teeth out/down.

I usually start a new barrel with a 100 shots at about 100 fps slower than normal to once fire brass and season the barrel and that lower speed seems to minimize copper at the muzzle end.