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Ruger Mark IV...Two Piece Bolts?

Discussion in 'Handguns: Autoloaders' started by SGW Gunsmith, Sep 28, 2020.

  1. SGW Gunsmith

    SGW Gunsmith Member

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    I caught wind of a rumor on the interweb the other day concerning that this owner found that his Mark IV with 10-inch barrel has a two-piece bolt.
    After what Ruger went through, and in some cases, is still going through, with some of the Ruger Mark II bolts separating, why would they go with a two-piece bolt on their newest iteration, the Mark IV?
    If any owners are here with the Ruger Mark IV 10-inch barrel, could you please check your bolt to see what you have?

    Thanks
     
  2. Riomouse911

    Riomouse911 Member

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    I pulled my bolt out (It took about three seconds! Man I love this Mk IV!)

    Here are pics of all sides, it sure looks and feels like it’s one piece of steel.
    E00B9D04-89B2-4074-800A-9CA6CD0B235C.jpeg 1DAF6835-A6CB-495C-A8B2-67BF0C9EF221.jpeg EB5B134B-B705-4EB7-AB29-BD56CAB9387A.jpeg DDB40F78-3B7D-4E88-B7E9-D32A3144302F.jpeg
    View attachment 945606

    The bolt has bluing on all sides except for what is visible through the ejection port, that part of the bolt is left white.

    There is a clip that holds the recoil spring and spring guide in place, that may be the reason the rumor started.

    I will say the grip frame is some sort of lightweight alloy, it’s not all steel like the stainless models are.

    Stay safe.
     

    Attached Files:

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  3. Project355

    Project355 Member

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    At one point in earlier versions the bolt and cocking tab were made from two parts. The bolt had a round extension that fit into a hole in the cocking tab and the extension was peened (aka, beat with a big weight) then ground flat with the cocking tab. Its not unusual to see a faint "circle" on the rear face of the tab.

    Technically speaking all of the bolts are one piece. They all have attached cocking tabs.

    Why? Because Bill Ruger would not have taken such a big piece of metal to turn it down just for some cocking tabs. Instead the piece was designed to be machined from smaller diameter bar stock and have the tabs attached. There's also an issue whereby a stress riser is avoided by using a separate attached piece for the cocking tabs.
    Any of the bolts that have the cocking tabs loosen or come off, are very easy to fix but people make much ado about it. I think there is a large portion of the younger generation that just does not know how to work with their hands and minds.
     
    Last edited: Oct 2, 2020
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  4. armedwalleye

    armedwalleye Member

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    My 10" MK IV is the Stainless flavor, and it's a one piece also, as Riomouse911's pictures display.
     
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  5. wiscoaster

    wiscoaster Member

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    Well, if they come here, they can be taught!! :D
     
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  6. Project355

    Project355 Member

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    And the beatings will continue until morale improves!
     
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  7. wiscoaster

    wiscoaster Member

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    :rofl::rofl::rofl:

    (I dunno, can I post that?)
     
  8. highlander 5

    highlander 5 Member

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    I've had MK II,III and currently a MK IV and the bolts were/are one solid piece. Now the bolt may start out as a casting and machined to finished product.
     
  9. zaitcev

    zaitcev Member

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    PPS-43 was a bolt made like that too. I don't see a reason to obsess with something being "one piece". In fact, it's better at times. For example, one of the brilliant pieces of the PK machine gun is a little claw that drags the cartridge out of the belt. It's made from a different steel than the bolt carrier, to which it is attached, and has a carefully selected temper. So, it can snap over the cartridge case a million times without breaking or wearing out. Machining it in one piece with the carrier would not yield the desired material properties.
     
  10. Project355

    Project355 Member

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    I think they were all made like that you just thought they were one piece because they were made very well. Unless you see the little circle in the back and most of the times it wasn't visible or it came apart.... Youd never know
     
  11. doubleh

    doubleh Member

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    This thread caused me to check my MK IV just to see what's what. Technically the bolt is two piece as the "ears" on the rear are a separate piece from the bolt. The line where they are put together is very fine but it's there. I didn't bother to look at my MK III but I would bet it's the same. It wouldn't be cost effective at all to machine the entire bolt from one piece of steel.
     
  12. Project355

    Project355 Member

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    Exactly. One piece for the cylindrical Part. One piece for the ears is the most efficient way to make that. What's more is that the ears to be investment cast, and just cleaned up a little bit.
     
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