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Thread: Mk1 & .22lr Kit

  1. #1
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    Mk1 & .22lr Kit

    Last December I purchased a discontinued MK1 slowfire upper with a .22lr kit for the MK1. The 9mm MK1 is a perfect slowfire and Iíve loved it from the start. The .22kit has been nothing but trouble though. After trying 5 different kinds of ammo and a few different magazines, I finally got it running. I was able to locate 1050rds of Remington golden bullets and that did the trick. Ran 5 mags through it and only had 2 stoppages but they were with the same mag. The mag seems to have a weaker mag spring. After removing that mag from the test group, the gun/Ammo/mags ran flawlessly. Canít tell you how happy I am to have this running 100%. The newer .22lr kits may not be as finicky on Ammo but this older style def was.

  2. #2
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    If you have not done so already, you might also want to try CCI AR Tactical .22LR 40 gr. ammo. It has worked well for me in a couple of semi auto pistols that had trouble with a number of other types of .22LR, as well as performing excellently in an M16 dedicated .22LR upper.
    Best of luck.
    MHO, YMMV, etc. Be well.

  3. #3
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    Anything to try with the bad mag? Do they make replacement springs?

  4. #4
    Registered User KickStand's Avatar
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    I have several videos about this. I’ll try to find a link.

    Put a small straw at the bottom of the spring. It will increase the spring pressure. I believe the mags are under sprung especially with time.

    See the second video at approximately the 1:50 mark.
    http://www.uzitalk.com/forums/showth...ock&highlight=
    Last edited by KickStand; 11-09-2020 at 11:11 PM.

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    I will say that I might have had rimlock too in earlier trials, but have strictly been using the McFadden loader and feel like that factor has been alleviated...

    Does anyone make replacement springs or is the straw fix basically doing the same thing as getting a new spring?

  6. #6
    Registered User KickStand's Avatar
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    Lage’s sells replacement springs for $5, per spring. I have received positive comments with the straw; however, OffMarksMan made a more robust Spring extension as did someone else. I’m not sure if they are selling them but contact offmarksman.
    The straw should work in the mean time and I’ve not change my straws in a few thousand rounds.
    Last edited by KickStand; 11-10-2020 at 07:21 PM.

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    I make a 3d printed spacer that increases spring pressure. It has helped some but has done nothing for others. Kinda hit or miss depending on what the real issue is.

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    Quote Originally Posted by KickStand View Post
    Lage’s sells replacement springs for $5, per spring. I have received positive comments with the straw; however, OffMarksMan made a more robust Spring extension as did someone else. I’m not sure if they are selling them but contact offmarksman.
    The straw should work in the mean time and I’ve not change my straws in a few thousand rounds.
    Took a bit to find the right sized straw but it was McDonald’s for the win...

  9. #9
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    Quote Originally Posted by Hood886 View Post
    I make a 3d printed spacer that increases spring pressure. It has helped some but has done nothing for others. Kinda hit or miss depending on what the real issue is.

    Tell me more. Got a pic?

  10. #10
    Registered User KickStand's Avatar
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    Quote Originally Posted by scottMO View Post
    Took a bit to find the right sized straw but it was McDonaldís for the win...
    I should have mentioned I used DD straws (Dunkin). I think itís the straws that come with a large drink. They work great and are a perfect fit.

  11. #11
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    Basically works just like the straw does just more robust. I have a suspicion that every gun probably needs a slightly different amount of spring pressure due to tolerances so technically I can make these in any length desired. So if you find a straw length that works well and want something more permanent then I can make one in that exact length. I don't have access to my computer right now and my phone gives me trouble posting pics. Feel free to pm me your number or email and I'll send you a pic.

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