Load Development Weirdness

[justinp61]

A bore scope is you friend.

This a shaw 260 barrel after 17 shots, the barrel had around 100 rounds through it at this point.

 

[terry 338rum]

a custom barrel should not foul like that after 10 shots. i three custom barrels by different barrel makers (338 rum,300wm,and 300wby) and i clean once year . the three together do not have that much fouling. i use berger bullets and h1000 and h4831 powder. i would talk to my barrel maker.

 

[Mike Matteson]

Following

 

[purpledragon]

All I shoot now is Hammer Bullets in all my rigs. The way they're designed there isn't a lot of bullet digging in the lands, so copper fouling isn't anywhere near what the other copper bullets leave in there......... JMHO

 

[Zen Archery]

How long is your strings?
Sounds like you've never let the barrel foul. Try running it dirty.

 

[capod28]

My patches after 10 rounds today
View attachment 493764

Assume the left-most patch (carbon) was the first patch you ran and subsequent patches (copper), left to right? Did you clean for carbon after cleaning for copper? Do you have a borescope to check if you may have more carbon under the copper fouling or maybe even a carbon ring?

Also, as Zen Archery suggests, try letting the barrel fully foul. Personally, I don't worry that much about copper, just carbon.

BTW - the copper fouling doesn't look all that bad to me...

 

[memtb]

New build. 300prc proof cf barrel on a defiance action

Shooting 199gr hammer hunters

About 110 fired so far. Awesome groups with 80gr of H1000.
Started out consistently at about 3050fps. Hit the jump and I'm at 3100. Very consistent std deviation between shots. About 5fps.

The weirdness is I can only get about 10 shots before the group opens up wildly. I'm talking 1.5" groups. While with a clean barrel I'm getting under 1/2" moa.

Came back and cleaned and more copper fouling. Talked to proof and they said I shouldn't be getting fouling that quick. They said they have guys that don't clean their barrels for a few hundred rounds.

Any ideas on what's going on?

I may be way off here, but I suspect that your barrel isn't as "quality" as you would like!

Many years ago in the infancy of the Barnes X bullets, they were notorious for excessive fouling! I had zero issues with my rifle, yet my wife and friends had fouling issues. The only significance of note was…..I had a "match grade" barrel, they were shooting factory produced rifles.

With some pretty serious hand lapping, their rifles started fouling less and shooting tighter groups! memtb

 

[Dirt_Nap]

I may be way off here, but I suspect that your barrel isn't as "quality" as you would like!

Many years ago in the infancy of the Barnes X bullets, they were notorious for excessive fouling! I had zero issues with my rifle, yet my wife and friends had fouling issues. The only significance of note was…..I had a "match grade" barrel, they were shooting factory produced rifles.

With some pretty serious hand lapping, their rifles started fouling less and shooting tighter groups! memtb

Where do proof cf barrels land on the quality spectrum?

 

[MOBE]

My son has a CA 300 wsm with a carbon barrel. It does the exact same thing. 1/4-1/2 minute 8,10,12 next shot will be 5" high and 5" right. Clean it and right back to center and accuracy returns. We just keep it clean. Didn't know what else to do. 4831sc and 175 smk

 

[Shane Lindsey]

Mine start to open on my carbon barrels, but I attribute it to the mirage from being hot. I do think that they take much longer to cool than all steel barrels.

Since it is a hunting rig, clean it, foul it with three and put it away. Next time out stretch distance with three shots, take it home and clean. Then keep working out further with very few shots. Not ideal, but if it shoots good for ten, that should be 9 more than needed when hunting.

Maybe try deep cleaning it with some JB bore paste. I recently had a rifle come into it's own with accuracy after some elbow grease with JB.

 

[memtb]

Where do proof cf barrels land on the quality spectrum?

I don't know! I haven't studied barrels, their quality ir lack thereof, for many years! My limited knowledge is based on what I read here (and other places) an some of the big (hopefully reputable) barrel manufacturers!

I qualified my comment with……I may be way off! And that is still valid!

Good Luck…..I hope that it's something simple and not a barrel issue! memtb

 

[Mike Matteson]

Some barrels want to be clean and other dirty. That's something you have to find out. It appears you did. So cleaning the barrel is going to happen more often. I seen it both ways. For what that worth.

 

[capod28]

This gentleman has probably forgotten more than most will ever know about gun maintenance/cleaning.

 

[cajun]

This gentleman has probably forgotten more than most will ever know about gun maintenance/cleaning.

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.