Cartridge Scoring

[TallGrassHunter]

Gentlemen. I have a problem I've never encountered before. Any help/thoughts on the matter will be most appreciated. Below are photos of cases as ejected from a Winchester 70 in 300WM (bought used and just my 2nd time shooting it). All of the spent cartridges have the same scoring. When I noticed it I first checked the remaining charged cartridges thinking maybe my dies were the problem; not so. The cases show no blemishes until shot. It's not affecting accuracy, as it shot a sub 1/2" group. Hopefully the photos show that the scoring is in the shape of a long, narrow S (-------------_______ kind of like this). Any thoughts or experience with this? Thank you in advance for any help, Richard.

 

[BobT]

Looks to me like there is a burr on one of the magazine rails or the feed ramp. Have you tried feeding a round in from the magazine and ejecting it without firing to see if the scratches show up?

 

[PeteG]

Looks to me like there is a burr on one of the magazine rails or the feed ramp. Have you tried feeding a round in from the magazine and ejecting it without firing to see if the scratches show up?

Feed ramp was my first thought.

 

[Clayton]

Magazine rails or ramp most likely. If the gun's not a control round feed, maybe the ejector plunger is forcing the case over against the edge of the chamber and/or forward ring of the action during extraction.

 

[TallGrassHunter]

Thank you all very much. I did as Bob suggested, fed an empty case, and sure enough the same scoring showed up. I really appreciate all the responses. Thank you each and every one for taking the time and sharing your knowledge.

 

[Clayton]

Glad for you. So long as it functions flawlessly I wouldn't worry to much about it.

 

[Longwalker]

I understand your search for excellence, but it really is a cosmetic issue and will not affect the function of the rifle. But I'd search for a solution too if I were you. A little polishing of the magazine rails and ramp should fix it up.

 

[nztimb]

A juducious polishing of the rails should sort that little blemish causing roughness. Under the edge and on the face will be the areas that need attention.

 

[postoak]

Try dropping a round into the chamber, closing the bolt, then ejecting the round and then seeing if there are scratches on the case.

 

[ChrisG]

It is from feeding from the rails as everyone else has said. I still get it on a lot of my rifles. Even with polishing you may get some scuffing. Cartridge brass is much softer than rifle steel. Stainless is harder than regular rifle steel but even regular steel once is has been blued or treated with something like melonite has a harder suface yet. Bluing is black Iron oxide or magnetite. It is harder than the steel beneath it by about 1.0 on the Mohs scale. In either case, the brass will likely get scuffed and as mentioned above, it is just cosmetic and has no effect on the function.