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Mak 90 in bad bad shape

Discussion in 'Gunsmithing and Repairs' started by MikeOBWan, Aug 4, 2012.

  1. MikeOBWan

    MikeOBWan Well-Known Member

    So I took my Mak90 out to the range today, and was trying out some of my new reloads in the gun. Well the first 9 worked ok. The last round actually exploded in the chamber. The bullet exited the gun and the bolt jammed about 20mm back but was stuck, and powder and smoke blew out of the receiver. No damage to myself just scared me..

    So I got home and pulled it apart. I got the Bolt Carrier group out, and low and behold. The entire back of the cartridge (rim, webbing and such) is gone. So basically just the body and neck of the brass is now stuck in the barrel.. How in the word do I get this removed from the barrel.. I can run a cleaning rod down the length of the barrel and it does not hit or hook on anything.

  2. rcmodel

    rcmodel Member in memoriam

    Get a new bronze bore brush for the cleaning rod.

    Run it in halfway past the case neck.
    Then pull it back out.

    If you are lucky, the brass bristles will snag it out.

    Sounds like your reloads need a little more development work!
    What was the load?

  3. MikeOBWan

    MikeOBWan Well-Known Member

    K.. I will try that... Dont think it will work though.. But it's worth a try.. I really don't want to have to take this to a gun smith.. Any idea is worth a try..

    My load is
    X-Treme 123 FP Plated
    AA2200 26.9gr.
    OAL 2.00900

  4. drsfmd

    drsfmd Well-Known Member

  5. rodinal220

    rodinal220 Well-Known Member

  6. Reloadron

    Reloadron Well-Known Member

    Good YouTube video from Midway. I have a collection of broken shell extractors which are the first step, that failing I use the technique shown in the video.

  7. firesky101

    firesky101 Well-Known Member

    The broken shell extractor worked well for me when a brown bear 7.62x39 failed in my SKS. I had to use my foot for leverage on the bolt handle, but it got it out.
  8. MikeOBWan

    MikeOBWan Well-Known Member

    There is no lip or rim left on the cartridge. The brass is sheered off at the barrel.

    I was unable to extract the brass using a cleaning rod and brass brush. I have ordered the Cerametal stuff as seen in the video and will try that when it comes in.

  9. Sam1911

    Sam1911 Moderator

  10. MikeOBWan

    MikeOBWan Well-Known Member

    Oh good call.. Thank you.. I will definitely give that a try..
  11. more importantly, you have to figure out what happened.

    could be you had an out of battery detonation due to a stuck firing pin, or an inertial firing pin with soft commercial primers (no return spring on the firing pin allows it to slam forward too early.

    could be a lot of things. how did the action open part way? what condition are the locking lugs in? is the front trunion in good condition? is the bolt damaged in any way?

    did you overload the case with powder, or use the wrong powder?
  12. mjsdwash

    mjsdwash Well-Known Member

    load up a round with no primer, and no powder, just case with a bullet. Crimp it real good, then load it pulling back the bolt and letting it slam forward. Force the bolt open by kicking it, or tapping the stock on the ground. Should pull the case out. Make sure there's no primer, since you may have an issue with out of battery firing.
  13. what the hell is that supposed to prove?
  14. Sam1911

    Sam1911 Moderator

    Sounds like he's saying that he's been able to get a fresh round to friction-jam into the inside of the broken case and get it to extract with the new round.
    Sort of a (REALLY) poor man's broken shell extractor. Doesn't sound like it would work all that well, to me, but maybe. At least the BSE can try to catch the case mouth. This method seems to be likely to jam things up even worse, but you never know.
  15. MikeOBWan

    MikeOBWan Well-Known Member

    Yeah I have the shell extractor coming.. Should be here Friday.

    I'm pretty sure what happened with the round is the bullet got pushed back into the case as it was chambered. I think I have to adjust my OAL and put a little tighter crimp on it..

    thanks for all the help
  16. rcmodel

    rcmodel Member in memoriam

    A tighter crimp isn't what you need.

    What you need is proper case neck tension in the first place.

    Take the expander out of the die and measure it.

    It must be at least .002" smaller then the bullets you are using or you won't have enough case neck tension to hold the bullet in place.

    If yours is too big, work it down with a drill & emery cloth until it is .002" smaller then your bullets.

  17. MikeOBWan

    MikeOBWan Well-Known Member

    Well.. So i got the broken shell extractor and it did not work.. I tried for about 2 hours with this thing and it would not hook the shell..

    So I had also purchased Cerrosafe alloy, and tried that also. No go. I got a perfectly good mold of the inside of the barrel and the inside of the casing. I took quit the effort to get the cerrosafe back out once i pored it. That damn case didn't even budge.. On the mold I noticed that I cannot differentiate where the case neck ends and the barrel begins, i can see a line in the mold but there is not indentation or anything. Is this correct..


    Not sure what my options are now..

  18. Sam1911

    Sam1911 Moderator

    Hmmm... plug the muzzle, fill the barrel from the chamber with PB Blaster or Kroil and let it sit overnight, then try the CerroSafe again.

    If that doesn't work, take it to a gunsmith.
  19. 45_auto

    45_auto Well-Known Member

    Do you have anywhere you can get some LN2 (liquid nitrogen)? Brass has a CTE of 19, steel is about 11. Plug the barrel just ahead of the shell casing, fill the chamber with LN2 and a tight bore brush will slide it right out.
  20. MikeOBWan

    MikeOBWan Well-Known Member

    Ok Well finally have an update on this issue. I have tried the extractor over and over to no avail. I was working on a deal to get with a guy who had some liquid nitrogen but we just never ended up hooking up..

    Long drawn out story short.. I plugged the stuck case right at the neck and then carefully filled the broken case with 2 part epoxy, making sure not to get any on the barrel itself. Let it setup for about 4 hours. Took a heavy duty cleaning rod, pushed it down the barrel till i could feel it in contact with my cleaning pad plug, then hit the rod a couple of times with a hammer and finally out popped the broken shell. I actually didn't even hit the rod all that hard..

    After doing about a half hour happy dance, i cleaned up the rifle and put it back together. Well test fire it this weekend.


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