Copper fouling location in barrel

[Tac-O]

I've got a pretty new barrel I'm trying to figure out the fouling issue in. It seems to foul very heavily with Speer and Hornady cup and core bullets. After 20 rounds, it's heavy enough that I feel the need to clean it. I'm also getting bad flier in every group of 4 shots that otherwise would be a stellar group. So, I think it's the fouling but not sure.

Anyway, looking through the borescope got me wondering about what we might learn from the location of the fouling in the bore.

In my barrel, the throat to probably the first 12 inches or so of bore has no copper. Then the copper fouling starts and gradually gets heavier, to where it almost looks gloopy near the muzzle. This is a nice, smooth mullerworks barrel and the chambering and throating job is rough. I've got probably 150 rounds through it. Performed a break in and also smoothed the throat a bit by lapping it.

So if the barrel is smooth but the throat and leade is rough, will that strip the copper off the jacket and just deposit it further down the barrel? Does the fouling description above indicate it's the rough throat and leade?

 

[Mikecr]

Sounds like you've polished the bore, causing copper to smear off.
If you didn't go too far with it, you might recover with ~10 shots of Tubb's FinalFinish (to rough it back up).

 

[Tac-O]

I only worked on the first couple inches of the bore around the throat, not the whole length and it fouled the same way prior to my "lapping". It did actually seem to reduce the fouling slightly, so I wouldn't think it's too smooth... It doesn't look like it anyway.

Is that type of fouling indicative of it being too smooth? Maybe I should get some pictures posted

 

[Mikecr]

FinalFinish® & FinalFinish® TMS Bullet Kits

By using David Tubb's FinalFinish & FinalFinish TMS Bullet Kits, you will experience better accuracy, reduced fouling and easier barrel clean up.

www.davidtubb.com

 

[L.Sherm]

So if the barrel is smooth but the throat and leade is rough, will that strip the copper off the jacket and just deposit it further down the barrel?

You answered your own question, try some JB in the throat area and I bet the copper fouling will decrease otherwise just keep shooting it will eventually subside but may take awhile depending on how rough.

 

[MagnumManiac]

Did you do a proper break in on the barrel?
Was the barrel lapped prior to being chambered?
Sounds to me like a barrel that hasn't had a proper break-in procedure.
I would clean with JB Bore Paste and a strong copper remover.
If the fouling persists, you may just have a rough bore.
The chamber and throat do not make the barrel foul, the barrel has not run in yet, but a shoot 1, clean for 5 shots, then shoot 3 and clean for 5 times and finally shoot 5 and clean for 5 times may help smooth out any roughness. Laying fouling over fouling is not helping your barrel run in.
My 22-250AI barrel can have 2 matches worth of shots run down it and the copper fouling is barely any, takes 5 mins to clean it. One of my 25-06's takes hours of scrubbing due to the myriad of machining marks from the factory, it shoots so good I just live with the knowledge it takes a lot of cleaning.

Cheers.

 

[L.Sherm]

A rough throat will definitely make a barrel copper foul, it deposits copper down the barrel. Thats why even on a brand new barrel the first 5-15 shots are the worst. No matter how perfect the chamber or reamer is there still a tad bit of roughness its not lapped like the barrel so your essentially firelapping it the first rounds.

 

[Tac-O]

Did you do a proper break in on the barrel?
Was the barrel lapped prior to being chambered?
Sounds to me like a barrel that hasn't had a proper break-in procedure.
I would clean with JB Bore Paste and a strong copper remover.
If the fouling persists, you may just have a rough bore.
The chamber and throat do not make the barrel foul, the barrel has not run in yet, but a shoot 1, clean for 5 shots, then shoot 3 and clean for 5 times and finally shoot 5 and clean for 5 times may help smooth out any roughness. Laying fouling over fouling is not helping your barrel run in.
My 22-250AI barrel can have 2 matches worth of shots run down it and the copper fouling is barely any, takes 5 mins to clean it. One of my 25-06's takes hours of scrubbing due to the myriad of machining marks from the factory, it shoots so good I just live with the knowledge it takes a lot of cleaning.

Cheers.

Yes the barrel is mullerowrks, so it was lapped and the bore is very nice.

I did a shoot clean break in for 5 rounds and have cleaned completely every 20 rounds since.

I had a minor amount of fouling with Sierra 180gr mk, Speer hot cor lays in on the lands heavily, and Hornady btsp laid it in the grooves and lands heavily.

It will definitely shoot 1/2" groups! I just don't want to have to clean every 5 rounds to avoid fliers :/

I may just get some of the Tubbs FF bullets rather than screw around with it forever. I don't think it could hurt!

 

[L.Sherm]

That would be the last thing I would do is shoot those bullets in a perfectly good barrel, thats not the problem its just the throat. Remember those bullets remove metal not only from the throat but the whole barrel.

 

[Tac-O]

That would be the last thing I would do is shoot those bullets in a perfectly good barrel, thats not the problem its just the throat. Remember those bullets remove metal not only from the throat but the whole barrel.

I didn't want to go that route, but after reading all the material on his site it sounds like he recommends it for good handlapped barrels with rough throats, so I thought it couldn't hurt. Maybe I'll think about it a bit more before pulling the trigger on them

 

[MagnumManiac]

I wouldn't do the Tubbs bullets, it will ruin your nice finish on the bore and rifling.
Does the chamber and throat have circumferential marks from being cut?
If it does, then it can be polished out in a lathe with either coarse scotch brute pads or emery cloth, depending on the depth.
A cross-hatch pattern is best when polishing out tooling marks.

Cheers.

 

[Tac-O]

This is how it started out before I had the Smith throat it deeper. The throating reamer he used was a lot smoother and cut some of the horizontal marks off... Maybe 50% of them at most

 

[L.Sherm]

The pics show your problem. You can tell by the pics the barrel was not the problem look how nice the grooves look. Somehow get the throat polished

 

[Mikecr]

Tubb's fire forming doesn't 'ruin' anything. Doesn't hurt anything. No matter the barrel.
In many cases it can only help.

I use FF for a 10sht break-in, and TMS as recommended for barrels already past that.
So far with Schneider, Pacnor, Broughton, Kreiger, Border, Lija, and Wilson. 4 of these barrels would rarely copper foul to begin with, and fire forming did not change that.
The reason is that the grit used with this sets the ideal surface profile,, just like the best in hand lapping.
Oh,, NEVER POLISH a bore.