Copper shedding

[shoot 51]

This is a buddies 308 in a REM 700 with its second barrel which is a Krieger. For the last 500 or more rds everything has been ok and the rifle shot sub moa. Lately,every 10 rds or so, he gets a head separation and an extreme flattened primer. I know his loading style and parameters and all is good. With my Hawkeye today we found a butt load of copper right where his free bore starts. (The picture is poor; iPhone to the Hawkeye)The second picture is the scratches from a rd loaded in the chamber and pulled back out. I’m at a loss

 

[Precision Underground]

Is so much copper built up that it’s jamming into that rather than the lands? Hard to tell anything from the pics. When is the last time it was cleaned and all copper removed?

 

[supercorndogs]

With case head separations, my first thought is always going to be that someone is bumping the shoulders too much. First thing to check is measure sized case vs fired case.

Every CHS I have ever seen has had an extremely flat primer.

 

[shoot 51]

He cleans it good after every shooting day. I boroscoped the entire barrel and there are no copper streaks anywhere. The only copper build up is exactly where the free bore begins and I’m telling you it’s heavy! The very top of the picture from the Hawkeye is the copper build up; the bright orange streaks.

 

[shoot 51]

With case head separations, my first thought is always going to be that someone is bumping the shoulders too much. First thing to check is measure sized case vs fired case.

Every CHS I have ever seen has had an extremely flat primer.

Exactly, from extreme pressure. I haven’t measure his cases myself but he insist his bump is .002

 

[KZP]

Does he clean it with a bore guide? Is it sticking in just far enough to prevent cleaning of that area?

 

[supercorndogs]

Exactly, from extreme pressure. I haven’t measure his cases myself but he insist his bump is .002

But the CHS is the cause of the pressure, not caused by the pressure. Another place to measure the case is at the base. If the chamber is too fat and the brass is expanding a bunch and getting sized back down, it will do it too. In general high pressure is not a cause of CHS. Not that you can't blow a case head off, but there is no primer in there when those happen.

That is also not to say that copper isn't giving him pressure, but I would be surprised if the CHS is related to it.

 

[shoot 51]

But the CHS is the cause of the pressure, not caused by the pressure. Another place to measure the case is at the base. If the chamber is too fat and the brass is expanding a bunch and getting sized back down, it will do it too. In general high pressure is not a cause of CHS. Not that you can't blow a case head off, but there is no primer in there when those happen.

That is also not to say that copper isn't giving him pressure, but I would be surprised if the CHS is related to it.

Did you see the pic of the scratch ring on the extracted bullet? Way up on the bearing area.

 

[Supersubes]

Did you see the pic of the scratch ring on the extracted bullet? Way up on the bearing area.

As supercordogs said, separations are a sizing issue. Ask yourself why a completely supported portion of the case would split, and in a perfectly circumferential fashion? It isn't pressure.

As far as the copper, something else is going on.

 

[Steel head]

Exactly, from extreme pressure. I haven’t measure his cases myself but he insist his bump is .002

I’ve had case separations with mild loads with cases that just should have been retired sooner.
They still had super flat primers.

Initial case stretch and or/bad sizing is what always seems to cause early case separations.

 

[shoot 51]

As supercordogs said, separations are a sizing issue. Ask yourself why a completely supported portion of the case would split, and in a perfectly circumferential fashion? It isn't pressure.

As far as the copper, something else is going on.

I’ve borescoped a lot and I have never seen copper like this and I’m without an idea of what’s happening.

 

[Supersubes]

I’ve borescoped a lot and I have never seen copper like this and I’m without an idea of what’s happening.

Is there enough inside chamfer on the necks? How is he cleaning?

Clean it completely and take some pics. Also, put one round through it after and then look at it.

edit: wonder if theres a burr at the end of the chamber? Like the reamer wasn't cutting well.

 

[shoot 51]

Is there enough inside chamfer on the necks? How is he cleaning?

Clean it completely and take some pics. Also, put one round through it after and then look at it.

edit: wonder if theres a burr at the end of the chamber? Like the reamer wasn't cutting well.

We shot long range together for at least 500 rds, same barrel and it shot sub moa and no problems

 

[KZP]

I’ve borescoped a lot and I have never seen copper like this and I’m without an idea of what’s happening.

Bumping my original comment, think it got missed.

Does he clean it with a bore guide? Looks like it sticking in just far enough to prevent cleaning of that area.

 

[shoot 51]

Bumping my original comment, think it got missed.

Does he clean it with a bore guide? Looks like it sticking in just far enough to prevent cleaning of that area.

I’ll check on that

 

[whatsupdoc]

Looks like throat is extremely short, hard to tell from the pics.

Is the bullet making hard contact with the throat?
Then when the bolt closes the round rotates and the bullet paints the throat with copper.

Did the reamer leave burrs in the throat?
Chamber/Throat area needs to be thoroughly cleaned then carefully inspected.

Case head separation is most likely caused from too much shoulder bump and may not be related to the copper buildup.
Just measure his loaded ammo and some fired cases to see if that is an issue.

 

[shoot 51]

Looks like throat is extremely short, hard to tell from the pics.

Is the bullet making hard contact with the throat?
Then when the bolt closes the round rotates and the bullet paints the throat with copper.

Did the reamer leave burrs in the throat?
Chamber/Throat area needs to be thoroughly cleaned then carefully inspected.

Case head separation is most likely caused from too much shoulder bump and may not be related to the copper buildup.
Just measure his loaded ammo and some fired cases to see if that is an issue.

After questioning him more last night, I found out he has brass that is .003-.004 bumps. That’s a big bump and maybe after repeated loading like that, it could be the chs problem. The copper shedding is definitely parallel to the barrel, wider on the breech side tapering off to a fine point towards the barrel. The ring of scratches on the bullet bearing surface is strange

 

[shoot 51]

I’ll check on that

He does use a guide and he is checking its depth

 

[37L1]

Can't really tell by the quality of the photo but does he have a carbon ring?

 

[ma smith]

does anyone clean the throat area (without the boreguide) using a chamber/ brush?

 

[shoot 51]

Can't really tell by the quality of the photo but does he have a carbon ring?

My first thought but I didn’t see one. I loaded a rd of his in his gun myself and the bolt action feels smooth

 

[shoot 51]

does anyone clean the throat area (without the boreguide) using a chamber/ brush?

I do

 

[37L1]

If it were mine, I'd get in there with a good brush and clean all that out just to see what's under all that copper. . .

 

[shoot 51]

If it were mine, I'd get in there with a good brush and clean all that out just to see what's under all that copper. . .

The copper was cleaned out and there was a huge carbon ring. He told me he never worried about that area.....he does now. Shooting Wed

 

[Slides]

The carbon ring was pretty obvious in the photo I'd say that was the problem.

 

[brianf]

I have to say it...and it’s been said a 1000 times before on this site.

If you have a carbon ring clean more often

if you clean and have a carbon ring, your not cleaning correctly or using the wrong chems.