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Posted: 7/30/2010 6:52:25 AM EDT
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When a spent shell casing is extracted, what causes the extractor to let go
of the casing? Does the extractor tip the neck of the case out the port, and then momentum flings the case away when the bolt stops? Thanks |
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When the bolt closes on a chambered round two things are happening at virtually the same time. The extractor hook is forced over the case rim, and the ejector (a plunger with a stout spring behind it, located in a hole in the bolt on the opposite side of the bolt face as the extractor) is compressed against the base of the case and back into the bolt. As long as the bolt is closed, the ejector is trying to push the case away from the bolt, but the chamber keeps it in place. When the bolt is unlocked, and starts to move rearward, the ejector is still trying to push the case away from the bolt, while the extractor starts trying to hold the case against the bolt. This ends up making the extractor a point around which, the case pivots. During most of the rearward movement of the bolt, the case can't pivot much, because the chamber and barrel extension keep the case roughly parallel to the bore. As soon as the bolt and extracted case are rearward enough that the front of the case clears the barrel extension, the ejector is able to fully extend, pushing the case away from the bolt. The case pivots to an angle where the extractor can no longer hold the case rim. At this point, the case has both rearward and rotational inertia, and maybe is also being acted upon by exhaust gas exiting the action and the case itself. All of this sends the case flying out of the action, to bounce off of the case deflector to hit the support pole beside you, and land down your shirt collar.
Karl |
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Quoted:
When the bolt closes on a chambered round two things are happening at virtually the same time. The extractor hook is forced over the case rim, and the ejector (a plunger with a stout spring behind it, located in a hole in the bolt on the opposite side of the bolt face as the extractor) is compressed against the base of the case and back into the bolt. As long as the bolt is closed, the ejector is trying to push the case away from the bolt, but the chamber keeps it in place. When the bolt is unlocked, and starts to move rearward, the ejector is still trying to push the case away from the bolt, while the extractor starts trying to hold the case against the bolt. This ends up making the extractor a point around which, the case pivots. During most of the rearward movement of the bolt, the case can't pivot much, because the chamber and barrel extension keep the case roughly parallel to the bore. As soon as the bolt and extracted case are rearward enough that the front of the case clears the barrel extension, the ejector is able to fully extend, pushing the case away from the bolt. The case pivots to an angle where the extractor can no longer hold the case rim. At this point, the case has both rearward and rotational inertia, and maybe is also being acted upon by exhaust gas exiting the action and the case itself. All of this sends the case flying out of the action, to bounce off of the case deflector to hit the support pole beside you, and land down your shirt collar. Karl This. Thank you Karl for explaining it. |
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