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Thread: HK21 Extractors and Springs

  1. #11
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    Quote Originally Posted by djohns11 View Post
    When I put the suppressor on it, I went through through another 120 rounds with no issue both on semi and full auto. What???? I give up.
    it doesn't have enough energy to cycle without the can. You confirmed this with the swap in 21/21e springs you said worked above

    Quote Originally Posted by djohns11 View Post
    Thanks! I'll try the 17 piece or as Ralph at RDTS told me to try a 9 first and go from there.

    you should try a regular 91 LP (thats what my 21 has) even then go to a 18 (50 degree/g3k LP)

    I know it sucks but your running a beltfed 308 "K" gun with and without a can, It's going to take some messing since you are running on the edges of the ability of the gun. The only way to change how it feeds is with the LPs.

    I would continue with the LP changes to get it to run, then you have to switch them when you have the can.
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  2. #12
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    Thanks! A couple others told me the same thing as they went through a huge learning curve as well. I'll try that in the next week and will get back with the results.

  3. #13
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    From the Maxim to the HK21/23 to the MG81Z, I've learned that patience pays off when tinkering with belt fed machineguns. A lot of forces are moving in opposing directions, high pressure gas involving a controlled explosion and metal parts are slamming against each other sometimes as fast as 30 times a second. A lot can go wrong with thse guns and diagnosis and treatment can be a challenge. Look at and appreciate the complexity of the HK/MM 21/23 feed mechanism. Lose one small spring and this gun fails to function properly - ask me how I know. When diagnosing, first take the gun apart clean it, inspect and replace any worn or broken parts and then reassemble. Any part slightly out of spec or several out of spec can result in a poorly functioning firearm. Everyonce in a while, a dirty part is to blame. Change/replace one thing at a time. Then repeat the firing process using the exact same ammo. You'll often the solution but it will time however, in the process, you'll discover how the gun really works. Also, I film most of my shoots for 2 reasons: posterity and to help diagnose a problem if something does go wrong. I also keep a machinegun diary in a spreadsheet format of the number of rounds fired, bolts (each is numbered), feed tray (each numbered), belts, recoil springs, etc. for every gun I have. I've learned over the years that some parts work together much better together than others. If all else fails, consult the proper smith or person knowledge about that particular firearm.
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  5. #14
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    djohns11 I think you have a variety of issues.
    Most seem to be setup/correct parts combination.
    Just need the right info.
    MM

  6. #15
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    maxfaxdude
    I totally agree. I started doing that and making progress. I have to give credit to TaylorWSO for his last suggestion. I did what he said and could not wait to do the test even though it's 10 degrees outside here and I was freezing. It worked! I was in shock as this gun has not worked correctly in over a year. I ran semi and F/A and it ran like a champ. I would not know what to do without the help and support of all on this forum. Many thanks!

  7. #16
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    hk21man

    Yes you are correct and I finally got it running correctly. I ran different types of ammo and no issues yesterday! both on semi and F/A. These are finicky guns but as you have said before when they run they run. I noticed a big difference as well with the short barrel compared to the long one. I'm not messing with anything now especially if I take a friend out and he or she pulls the trigger and it just goes click....
    Here is the setup: new extractor, new extractor spring, new ejector and extra strong spring, I am using a MM23E recoil spring made to fit. Spring tested with a compression setup at machine shop which was less than a HK21E but more than an HK21 spring. Interesting. Also using a G3 locking piece for normal use and a #9 for supressor. Thanks to all! Any further suggestions much appreciated!

  8. #17
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    "I am using a MM23E recoil spring made to fit."

    If I may ask, what does this mean?

  9. #18
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    Quote Originally Posted by har1340 View Post
    "I am using a MM23E recoil spring made to fit."

    If I may ask, what does this mean?
    yeah me too

  10. #19
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    djohns11 contact me and I can give you correct setup per ea. config.
    I would bet most problems have nothing to do with the extractor/spring and ejector springs.
    MM
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  11. #20
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    Quote Originally Posted by hk21man View Post
    djohns11 contact me and I can give you correct setup per ea. config.
    I would bet most problems have nothing to do with the extractor/spring and ejector springs.
    MM

    did you not read the thread? He fixed it with the correct LPs and recoil springs

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