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Posted: 2/9/2010 9:34:00 AM EDT
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i have some 308/7.62 cases, and noticed a couple of them have several vertical grooves all the way around the shoulder
i thought they might be some kind of crimp, but that doesnt really make sense so the question is, what are they? 
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I have some of those. After cleaning the soot you can see that the case actually expands into those grooves upon firing. They wont iron out when you size but they should after you fire them in a non fluted chamber.
ETA: be generous with the lube when you size, they can be a little tough |
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like that, but are only on the shoulder and neck what are they for?
or were they just used in a fluted chamber? like the poster above said and what rifle in the military uses a fluted chamber? |
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Quoted:
HK G3/Hk-91 types and derivatives CETME in .308 have fluted chambers, IIRC. The design is to help the autoloader continue to run in dirty conditions. To be more accurate, it "floats" the neck and shoulder of the case, allowing for the HK roller-lock system to extract easily without the camming action of a rotating bolt system. It also allows the gun to operate dirtier, but that's not the main reason. |
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