Understanding the HK23e extractor
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Thread: Understanding the HK23e extractor

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    Default Understanding the HK23e extractor

    Just trying to understand how the HK 21e/23e extractor works. While with all the HK's with bolt heads, I can see how things work (well). Is there anytime in the guns operation that "makes" the extractor help the empty case extract? Is it a combination of when the ejector is in it's specific location that both work together?
    Thanks

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    The improvement(s) to follow as I see them

    Mechanical advantage (most important):

    The purely lateral/outward force encountered on the 91 style extractor spring is changed in the E series to a "offeset" force where a lever (from extractor tooth to the pin) makes the force smaller on the spring/spring can impart a larger force to the extractor. Also the "hook" on the end of the E extractor acts as a stop for the extractor as well at full extension. This means on a 91 extractor, the spring will take 100 percent of the outward force if you have a jam and a E spring has a limit to what the spring will take, preventing permanent deformation of the spring. The pin will break before the spring will encounter deformation.

    spring design:
    The spring design is also significant, the flat/cantilever style 91 spring is not as strong as a E compression spring when comparing equal sizes, even when the additional lever force is applied. The smaller coil spring will last longer than a flat spring.

    Lastly the additional material on the E series face allow it to be stronger where the rim of the cartridge strains the extractor. I'm sure the metal is better as well but don't know the specs.

    The E extractor works better dues to mechanical advantage, that prevents the failures in the 91 series. HK should have made all their bolts this way, or at least retrofitted them. The MAD bolt is a good example of how great the advantage is.

    ETA crappy picture (not to scale/numbers are a guess) F=extraction force
    Last edited by TaylorWSO; 06-14-2020 at 04:43 PM. Reason: add picture
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    Quote Originally Posted by TaylorWSO View Post
    The improvement(s) to follow as I see them

    Mechanical advantage (most important):

    The purely lateral/outward force encountered on the 91 style extractor spring is changed in the E series to a "offeset" force where a lever (from extractor tooth to the pin) makes the force smaller on the spring/spring can impart a larger force to the extractor. Also the "hook" on the end of the E extractor acts as a stop for the extractor as well at full extension. This means on a 91 extractor, the spring will take 100 percent of the outward force if you have a jam and a E spring has a limit to what the spring will take, preventing permanent deformation of the spring. The pin will break before the spring will encounter deformation.

    spring design:
    The spring design is also significant, the flat/cantilever style 91 spring is not as strong as a E compression spring when comparing equal sizes, even when the additional lever force is applied. The smaller coil spring will last longer than a flat spring.

    Lastly the additional material on the E series face allow it to be stronger where the rim of the cartridge strains the extractor. I'm sure the metal is better as well but don't know the specs.

    The E extractor works better dues to mechanical advantage, that prevents the failures in the 91 series. HK should have made all their bolts this way, or at least retrofitted them. The MAD bolt is a good example of how great the advantage is.

    ETA crappy picture (not to scale/numbers are a guess) F=extraction force
    Taylor: Excellent explanation. Well done from an engineering point of view.

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    Thanks just what I was looking for.

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    man i feel like a mental underachiever in life after reading that. dang it.

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    As many folks have pointed out over the years, the mechanical advantage of the E extractor design over the old flat "spring" design begs the question why HK never adopted the idea with their non-belted bretheren. Didn't the E guns come out in the 80s?

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