Load Development Weirdness

[capod28]

Maybe so. But I bet he doesn't have any hand lapped custom barrels either. Like a lot of old guys( me included) we sometimes don't know what we don't know. I know I shot the original barnes x bullets in factory barrels and the copper fouling was horrible. I do believe that some folks obsess about cleaning to bare metal which I don't believe is necessary. Let the rifle tell you what it needs. In this case losing accuracy after 10 rounds in a custom barrel is unsatisfactory. Be curious to see if this is load specific.

I'm an old guy too and agree we sometimes don't know what we don't know. But, I have a hand lapped custom barrel and have not had a problem with copper build-up increasing group size. Have not shot solid copper bullets, though.

I would tend to wonder if the OP has done a good enough job removing carbon (assuming he hasn't checked with a bore scope). Sometimes carbon rings can form pretty quickly. I would also like to see him shoot more than 10 rounds to see if his groups start closing up again.

 

[Mark37082]

Cleaning regimens are as diverse as anything in rifle shooting. The more I read the more I scratch my head. I have always cleaned my barrels after each range session. I don't get carried away with using caustic solvents especially with long soak time. I have never run into situations where my groups dramatically opened up without a plausible reason (heat, loose scope mounting, excessive carbon fouling, or stock contact with the barrel). Most of the time my problems were shooter errors.
I hope you find the solution.

 

[victor3ranger]

That's what I am wondering, send 10 more rounds to see if it tightened back up, might have to pave the road so to speak

 

[Mikecr]

Carbon fouling doesn't double or triple group size.
Copper fouling can, and it's like a switch thrown when it does.

I've dealt with (2) factory barrels that did me like OP's barrel.
One I fixed with fire lapping, the other I pitched in a dumpster across town.
When barrels were replaced to aftermarket, never seen all the copper again, and never copper fouled out again.
That was the easiest fix

 

[Calvin45]

Carbon fouling doesn't double or triple group size.
Copper fouling can, and it's like a switch thrown when it does.

I've dealt with (2) factory barrels that did me like OP's barrel.
One I fixed with fire lapping, the other I pitched in a dumpster across town.
When barrels were replaced to aftermarket, never seen all the copper again, and never copper fouled out again.
That was the easiest fix

Didn't know that. I don't fully understand but I beleive you and think I've seen some things that reflect what your saying.

But I wonder why carbon isn't such a big deal? It gets baked on there pretty dang hard! But I suppose it's not nearly as "binding" or tacky/sticky as copper?
I don't know. But I do know that for those guys that make a box of shells last a decade cleaning their rifle does more to harm accuracy than help it (not that it matters much either way for these people haha)

I have seen the "thrown a switch" effect but didn't know if carbon, copper, or both were to blame. But in a .300 win mag that I hadn't cleaned in a long time, everything just kept shooting MOA or better…and then just like you say, a switch flipped and it was shooting like 6-8 inch groups at 200-250 yards or so (red neck measuring in paces)

I checked the scope rings and bases and stuff, checked the pillar screws underneath, checked that the barrel was in fact free floating, checked this checked that….

Imagine my embarrassment when I cleaned my bore really thoroughly and the beast went right back to the way it was before, after a few fouling shots.

I realized it had probably had somewhere between 150-200 rounds through it since it's last cleaning. Just forgot.

 

[Mikecr]

Carbon is the ultimate killer of accuracy, as it's permanent by the time you notice it.
We all do -eventually,, with every barrel passing it's accurate life.
With carbon you see a sudden 1/8 to 1/4moa opening. You could put up with it for another 1,000 shots and maybe see 1/2moa opening by then.
It's permanent because efforts to remove it by then are a greater detriment than the carbon itself.

With copper, it's only temporary, but big when it hits. It's an acute problem moreso than chronic.
Because I've fought it the past, I'm sensitive to it, and will not put up with a barrel that picks up more than 2 patches of blue from 50 shots.
I also do not subscribe to leaving copper, primer junk, or even carbon in a barrel for extended periods.

Things I do in this regard;
Use of top brand aftermarket barrels (where I can)
I break in all barrels with 10shts of Tubb's FinalFinish
After ANY shooting, I clean bores to white metal, and dry prefoul with Tungsten Disulfide (WS2)
I coat bullets with WS2

 

[victor3ranger]

Have you used the Tubbs final finish in a factory barrel?

 

[Calvin45]

Carbon is the ultimate killer of accuracy, as it's permanent by the time you notice it.
We all do -eventually,, with every barrel passing it's accurate life.
With carbon you see a sudden 1/8 to 1/4moa opening. You could put up with it for another 1,000 shots and maybe see 1/2moa opening by then.
It's permanent because efforts to remove it by then are a greater detriment than the carbon itself.

With copper, it's only temporary, but big when it hits. It's an acute problem moreso than chronic.
Because I've fought it the past, I'm sensitive to it, and will not put up with a barrel that picks up more than 2 patches of blue from 50 shots.
I also do not subscribe to leaving copper, primer junk, or even carbon in a barrel for extended periods.

Things I do in this regard;
Use of top brand aftermarket barrels (where I can)
I break in all barrels with 10shts of Tubb's FinalFinish
After ANY shooting, I clean bores to white metal, and dry prefoul with Tungsten Disulfide (WS2)
I coat bullets with WS2

Yeah this was a while ago…since then I've started treating bores and bullets with hex boron nitride and it really makes a big difference regarding cleaning too (I did a big write up on it week or two ago).

I'm not sure I'm fully on board with the idea that carbon is permanent. But I can certainly see how efforts to remove it can go very wrong.

 

[Mikecr]

Have you used the Tubbs final finish in a factory barrel?

Yes, and the best in aftermarket as well. Every barrel.
It might help, or not, but it doesn't hurt.

I'm not sure I'm fully on board with the idea that carbon is permanent.

The carbon we clean out is not permanent obviously.
But what impinges into the hot bore surface, eventually leading to constrictions, might as well be permanent.
Digging so deep to remove it would destroy the metal.

I know of nothing that can be done about it.
We can well manage carbon with our cleanings, and that get's us expected accurate barrel life (which is different from general barrel life).
Someday, maybe someone will come up with a protective coating that actually extends accurate barrel life.

There is a third barrel that I learned about copper with.
This was an awesome aftermarket at about half expected life.
One day I got overzealous with the borescope, and abrasive cleaning with Flitz (a polish).
It ended up that stupid move ruined the barrel immediately.
Took it to permanent copper mine that even fire lapping could not undo..

 

[Calvin45]

Yes, and the best in aftermarket as well. Every barrel.
It might help, or not, but it doesn't hurt.

The carbon we clean out is not permanent obviously.
But what impinges into the hot bore surface, eventually leading to constrictions, might as well be permanent.
Digging so deep to remove it would destroy the metal.

I know of nothing that can be done about it.
We can well manage carbon with our cleanings, and that get's us expected accurate barrel life (which is different from general barrel life).
Someday, maybe someone will come up with a protective coating that actually extends accurate barrel life.

Okay I'm picking up what you're saying here. So the stuff that "impinges" (I'm not fully sure on the meaning of the word here, I assume it's like impact-impregnates the steel itself?) - is this stuff visible still or like a microscopic kind of film? I ask because I'm pretty convinced I've seen barrels cleaned down to bare metal but nonetheless based on what you're saying they still have "permanent" carbon deposition?

Also I had never heard the theory that it was carbon that was responsible for the end of accurate barrel life, I've always been under the impression that that had waaaaaay more to do with throat erosion, firecracking, and the deterioration of the lands over many firings.

Not trying to argue or come off as argumentative, I just legit do not know very much about all this and what you're saying all at once makes a ton of sense to me…but also doesn't.

 

[Mikecr]

First I'll offer my definition of accurate barrel life. This is a point where peak accuracy leaves for good.
The barrel may still shoot well enough, and most have never seen peak accuracy to miss it anyway.
But the point exists. It's real. Cutting edge competitors can see it right to the group (like a switch thrown).
I calculate it, and watch it happen right on cue, to the shooting session.
A buddy of mine who would daily bring in fantastic wallet groups, seen the switch flip, and very early, after mismanaging use of moly.
Moly can kill a barrel's accurate life from a similar reason as carbon.

Land erosion can mess you up -if you're load relies on an exact land relationship.
Otherwise, your lands can move several inches down the barrel and sometimes there is no ill affect at all.
Firecracking can strip copper and even cause bullets to blow up, if on the edge of doing so anyway.
But if your cartridge uses little of a cool burning powder, and your pressure and shot timing is moderate, you could see nearly no erosion -when accurate barrel life still passes away.

If you were to slug a bore when it passed accurate barrel life, I'm sure you could detect an early constriction. Beyond that constriction the damage is already done. The bullet is looser, and barrel timing becomes erratic.
The location is likely where gas vapor condenses to form a ring.
You can lap it out, and possibly recover for a very short time. But it's more likely bullets will hate that spot, and barrel timing will still suffer.
Lapping, and barrel setbacks won't buy you long, and then you're expending more efforts, and wasted efforts, than barrel replacement.