Markings on fired case necks?

I picked up some .308 brass at the range because it looked pretty clean and I figured I'd re-use it eventually. Some of it has stright black lines from the case neck to about 1/2 way back. Some of it cleaned off, while some of it is textured; it feels like they're indentations into the metal.

I assume this is rifling of some sort, but its only on some brass. Is this sort of thing normal? Only happens on certain types of brass? Or rifles?

Here's what I'm talking about (these pictures aren't exactly clear but I think you'll be able to see what I am talking about):
www.panix.com/~jmw/308_brass1.jpg www.panix.com/~jmw/308_brass2.jpg www.panix.com/~jmw/308_brass3.jpg

Some military rifles like the HK have grooved chambers to make case extraction more reliable - it leaves those marks on the brass like you describe. The brass may be expanded slightly more, but it is reloadable.

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Looks similar to what I've seen from brass that was fired in an H&K 53 (except that was a .223). Probably fired in a fluted chamber such as is used on H&K's and CETME's.

James

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# # I picked up some .308 brass at the range because it looked pretty clean and # I figured I'd re-use it eventually. Some of it has stright black lines from # the case neck to about 1/2 way back. Some of it cleaned off, while some of # it is textured; it feels like they're indentations into the metal. # # I assume this is rifling of some sort, but its only on some brass. Is this # sort of thing normal? Only happens on certain types of brass? Or rifles? # # Here's what I'm talking about (these pictures aren't exactly clear but I # think you'll be able to see what I am talking about): # It is from the fluted chambers of HKs and possibly other guns. Nothing to worry about.

Chuck Jax, FL

They were fired in an HK91. Fluted chamber

> ... clean and > ... lines from > ... some of > ... this > ... rifles? > ... I > ...