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Ruger M77 light hammer strike

Discussion in 'Gunsmithing and Repairs' started by jstein650, Mar 21, 2013.

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  1. jstein650

    jstein650 Member

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    I have a M77 MkII in .223. It doesn't hit hard primers, like military rounds, hard enough to fire. I found out with blanks that if I put pressure on the rear of the striker with my thumb, it will. I have chosen not to worry about it since it ALWAYS will fire with WSR's, Rem., (and regular CCI's usually), so I just stuck with Winchesters. Well now, all I could get was CCI 450's, and of course, no fire. I did put a Timney trigger on it a long time ago, which is great, but I think that somehow this problem showed up after that. No change was made to the spring, and the assembly is clean and lubed. Any ideas?
     
  2. rcmodel

    rcmodel Member in memoriam

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    Possibly the Timney trigger is not holding the striker cocked back as far as the factory trigger so you have less spring tension?

    Or perhaps it is set with too little over-travel and somehow dragging on the cocking piece when it releases and slowing it down.

    Can you swap in the factory trigger and see if it works with it?

    Should you do that, mark the position of the cocked striker with the Timney and then see if it is further back with the Ruger trigger sear in it.

    rc
     
  3. jstein650

    jstein650 Member

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    I have a feeling there's some dragging going on. Now, I'm embarrassed to say this, but I think I buggered up the tiny overtravel allen screw socket by using a too small wrench.:eek: My factory trigger is somewhere in my stuff back in Indiana. What do you think of the prospect of doing some very careful flat sanding with super fine paper on that cocking piece? Am I asking for trouble?

    P.S. I know it's a striker, not a hammer, but 'striker strike' sounded funny.
     
    Last edited: Mar 21, 2013
  4. rcmodel

    rcmodel Member in memoriam

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    No, don't file or sand anything until you find out what is going on.

    Color the striker & Timney sear with a black marking pin and cycle & snap it a couple of times.

    Then see if the ink rubbed off on the bottom of the cocking piece or top of the trigger sear.

    But still, it behooves you to put the factory trigger parts back in and rule all the bolt & striker parts limiting cocking distance out of the puzzle, if you can find them.

    If it works with the stock trigger?

    Well there a real good clue it has something to do with the after-market trigger.

    Well thats ----- Unfortunate.
    It could very well be the over-travel adjsutment set to close to fully release the sear.

    rc
     
    Last edited: Mar 21, 2013
  5. jstein650

    jstein650 Member

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    "Well thats ----- Unfortunate."

    LOL!, Yeah. That's about what went through my mind... Of course, one wants the smallest amount of overtravel possible, so....

    I will try what you mentioned with the marker.. I can see, however, that there is a very slight bit of wear on the cocking piece, on about the first 1/8" of it's travel. It's polished quite smooth and very shiny as it is, so it should be easy to see any drag.
     
  6. Sun Tzu warrior

    Sun Tzu warrior Member

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    I will just comment on the "buggered up" set screw, The machines I work on have a lot of set screws that get boogered up (stripped) all the time, If you can find one, they make a type of "easy out" bit for stripped out hex head set screws. If not you can hammer in an appropriate sized torx bit and remove it easily. Replace wit,h new set screw.
    Hope this helps.
     
  7. rcmodel

    rcmodel Member in memoriam

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    Good plan Sun Tzu warrior!

    Get the screw out and go from there if you can't find the factroy trigger parts.

    rc
     
  8. jstein650

    jstein650 Member

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    Yes, excellent. I thought I was sunk with the screw. Thanks for the info, that will help!
     
  9. sage5907

    sage5907 Member

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    When all else fails install a new Timney firing pin spring. I had a firing problem was a FN Mauser Supreme action with a Timney trigger and a new Timney firing pin spring solved the problem. The rifle works better than before with a really quick lock time. It hasn't been slow to fire since the new spring was installed and fires with every pull of the trigger.
     
  10. Coltdriver

    Coltdriver Member

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    I have an M77 Mk II in .223

    The chamber in mine is cut where with my Winchester 5.56 ammo the bullet ogive is in the lands. With .223 Rem its fine. I stopped shooting the
    5.56 ammo.

    Sounds like you may have one with a chamber cut a bit more generously.

    Do you ever have the problem with regular .223 or do you think its purely a firing pin strike problem?
     
  11. rodregier

    rodregier Member

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    I had a Ruger 77 MKII in .308 Win that would not reliably set off NATO-spec primers, but was fine with commercial primers. I found out that Ruger had quietly changed the specification weight of the striker spring over the years. The newer production striker springs or Wolff "+" spring should solve the issue assuming there isn't another underlying issue.
     
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