Unusual marks on brass?

Hey all,
Hope everyone's feeling good.

I was sorting out a bunch of brass today, some of it was from a buddys new gun. I don't own a 9mm, never owned one but I have a friend with a sig 226 threw all his brass in my bag because he thought I'd use it. Sorting it out of my brass I noticed all cases had the same marks, rough chamber? It worked fine, no trouble but I was just curious as to what the deal with the marks is.

Thanks

troy fairweather said:

Could it be from the magazine?

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I guess it could be from anything, I don't know. I just haven't really seen that type of scratches before. It isn't my gun, just curious if anyone knew. Seems too consistent and if think if it were from the magazine there would be more of a dragged look from when it's pushed from the magazine . my initial thought was a chamber burr or chatter mark but I'll have to ask my buddy if I can look at it next time I'm over there.

ontarget said:

Could it have already been there? Not even caused by the gun?

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I'd think not, I'm looking at about 100 cases, all of them with the exact same marks. Wouldn't think factory ammo would be scuffed like that.