What causes this brass-stripping off case head?

[KY_Windage]

Rem 700, factory barrel and bolt with no modifications (other than I replaced the extractor to see if that would help -- it didn't).

Cases fired a few times in this chamber come out a consistent dimension (measured after de-priming, but before sizing), and I set the shoulders back .0025 - -.003" short of that with the FL die.

Nearly every case has a swipe mark on its face (none on the side of the rim), though some do not show in the photo. Lots of little specs and flakes of brass around the ejector, and some find their way into the bore and come out on my cleaning patches - tiny flakes shining when I hold the light right.

I routinely remove the ejector and its spring and clean bits of brass out of the hole, but after a few firings the debris is right back there, all around the ejector.

It SEEMS to be that the ejector hole rim is what is scraping the brass off the face of the case. I don't know what else it could be. But the rim itself feels and looks perfect -- no high-spot or ding in it. The top of the ejector is smooth as can be.

I figure someone must have run into this before . TIA for any advice.

 

[JohnKielly]

That first shot looks like the ejector hole does have an edge & that's what is marking a circle on some cases & other issues.

How would you be dropping the ejector out again and gently countersinking the hole the smallest amount with a brand new drill of suitable size or other sharp device?

 

[KY_Windage]

That first shot looks like the ejector hole does have an edge & that's what is marking a circle on some cases & other issues.

How would you be dropping the ejector out again and gently countersinking the hole the smallest amount with a brand new drill of suitable size or other sharp device?

I'd be good with that, and was thinking of it but did not want to try it before asking, in case I was missing something.

 

[gunsandgunsmithing]

Pressure

 

[243winxb]

Nearly every case has a swipe mark on its face

The ejector hole looks odd. May need to be smoothed off some?

Or - High pressure sign. Primer pockets will become loose in 5 firings or less.

 

[Shawnba67]

That brass says Norma on it, You cannot trust Norma ejector marks as a gospel.
However ejector marks are a high pressure sign so verify everything else carefully! Chronograph!!!!!!!!
I have had Norma 6xc brass with worse ejector marking at starting loads! Really tore my hair on that one.

 

[Jesswil61]

The primers in the first view do not appear flattened or to be backing out and the firing pin dimples are crisp. This really does not appear to be a clear pressure issue, if the loads are working the path mentioned above to carefully debur the ejector and possibly take some steel wool to the ejector itself should be a fix. If it does not go away at that point you could bring the load down some and have better brass life as well.

 

[NorCalMikie]

Will the fired case fit back in the chamber without pressure on the bolt handle?
Thinking brass too short and getting slammed against the ejector rod. Maybe brass "too short" (headspace) and moving in the chamber before it's fireformed?

 

[jpretle]

Some of those case heads show a circular extrusion into the ejector hole. A certain sign the brass is flowing, due to pressure.

 

[whatsupdoc]

Before you do anything to the bolt try different brass.

 

[jpretle]

Before you do anything to the bolt try different brass.

Or maybe back off on the powder charge.........

 

[drover]

Or maybe back off on the powder charge.........

It looks like pressure to me, back off a grain or so and see if you are still getting the ejector marks on the brass. That is by far the easiest way to determine if it is a pressure issue.

drover

 

[Bill K]

Pushing high pressure, for the load, in your rifle. Back off some.

 

[MGYSGT]

Primers still have round edges. If it is pressure, then those are some tuff primers.

 

[KY_Windage]

Hodgdon says for 1:9 24" bbl (mine is 1:9 26"), 130-gr and H4350, the recommended start is 39.7 gr. and max is 42.7 gr. I am shooting 42.0.

Cases will go back in w/o resistance to closing.

It is even doing the swipe on deprimed, tumbled brass.

All the above lead me to believe it is not pressure related.

It has got to be the ejector hole rim, right?

 

[Stephen Frith]

Hodgdon says for 1:9 24" bbl (mine is 1:9 26"), 130-gr and H4350, the recommended start is 39.7 gr. and max is 42.7 gr. I am shooting 42.0.

Cases will go back in w/o resistance to closing.

It is even doing the swipe on deprimed, tumbled brass.

All the above lead me to believe it is not pressure related.

It has got to be the ejector hole rim, right?

Not pressure related. Chamfer the rim of the ejector hole a bit and your world will right itself.
Luck,
Stephen

 

[Bill Norris]

Rem 700, factory barrel and bolt with no modifications (other than I replaced the extractor to see if that would help -- it didn't).

Cases fired a few times in this chamber come out a consistent dimension (measured after de-priming, but before sizing), and I set the shoulders back .0025 - -.003" short of that with the FL die.

Nearly every case has a swipe mark on its face (none on the side of the rim), though some do not show in the photo. Lots of little specs and flakes of brass around the ejector, and some find their way into the bore and come out on my cleaning patches - tiny flakes shining when I hold the light right.

I routinely remove the ejector and its spring and clean bits of brass out of the hole, but after a few firings the debris is right back there, all around the ejector.

It SEEMS to be that the ejector hole rim is what is scraping the brass off the face of the case. I don't know what else it could be. But the rim itself feels and looks perfect -- no high-spot or ding in it. The top of the ejector is smooth as can be.

I figure someone must have run into this before . TIA for any advice.

I ran into this issue with a new Rem 700 5R 308 about a year ago. Except mine was so bad that if I put a brand new piece of prepped (dimensions checked and expander run in necks and neck sized with a bushing die) Lapua brass in the chamber and closed the bolt it would shear brass off of the case head. After firing it I would have to beat the bolt open. Remington Customer Service told me if I shot Factory Ammo in it my issue would go away. LOL. I told him I had been handloading for over 25 years and he could take his assumption and cram it where the sun did not shine, but not so elegantly.

 

[Ggmac]

High Pressure for the brass youre using

 

[KY_Windage]

Not pressure related. Chamfer the rim of the ejector hole a bit and your world will right itself.
Luck,
Stephen

I did, now no more damage to my cases. What I had no clue to was that those tiny brass chips I was getting out of the barrel were destroying my accuracy. My last 5 shots at 200 yds today:



Thanks, guys!

 

[tobnpr]

The primers in your pictures didn't support the overpressure theory.
I don't understand the argument that ejector swipes are indicative of overpressure to begin with.
Extractor marks/gouging- absolutely. High pressure makes the case difficult to extract.

The ejector does nothing to the case until primary extraction has already occurred.
It is the naturally occurring motion of the ejector pin to swipe across the casehead as the brass clears the receiver cutout and can be pushed outward. I've got an AR in 6.5 that routinely needs brass shavings cleared from the boltface due to a very stiff ejector spring; I suppose I could disassemble the bolt, take a couple turns off the spring but I just don't consider it anything that needs to be "fixed".

Someone explain to me how swipe marks from an ejector are related to excessive pressure?