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Posted: 10/8/2008 8:24:08 PM EDT
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After sorting some brass bought here on the EE, I found about a dozen of these, the one on the right is in the original state, the one on the right has been decapped and resized. The resized one does chamber and eject like all of my other good brass. They have 12 flutes bulging on the OD, the ID is unchanged except at the shoulder angle, the flutes can be felt with a paper clip there.  Was this from an HK or what? I plan to use these as setup pieces but I was just curious as what made these that way, and should they be scrapped out? Again, I do plan to scrap them though...... TIA, EDIT: these are .308 brass and was bought to be fired in an M1A. |
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I guess in a related question, What is the major benifit of using such a chamber? Does the colleted chamber really make feeding/extraction that much more reliable? Or is it for someone that is too lazy to clean their equipment & keep it in good working order? It just seems like a waste of brain cells & effort when the old fasioned way seems to still work pretty good. MLG |
They have to be sized to the correct length for setting up a trimmer. It might work, it might not, you'll have to experiment. |
The chamber has to be fluted to let the roller locked action extract the brass. If the chamber isn't fluted, the gun would rip rims off of the cases. |
To explain in a little more detail, with the roller-retarded systems used in HK and CETME the bolt is never locked. As such the bolt begins moving backwards at the same instant the bullet starts moving forward, so the case is being extracted while under full pressure. If a normal obturation cycle took place, the case would stick to the chamber walls while the case head was pulled back, ripping the case in two. This is why HKs should not properly be called "roller locked" actions, because the action is not locked by rollers or anything else. It is also why they are not "delayed blowback", despite the many, many people calling them that. If they were delayed, this wouldn't be an issue. To be precise, they are "retarded blowback" actions, because the bolt begins blowing back immediately, but does so at a mechanical disadvantage, which retards the cycle. |
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