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Thread: Bushing firing pin?

  1. #16
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    Quote Originally Posted by Kevin Gullette View Post
    ......I posted the following on the saubier(small caliber)board.

    As a reference, and a good read, refer to Precision Shooting magazine, May 2001, page 31, "The Real Reason Primers Pierce" by Jerry Stiller.......you know....the guy who designs actions.

    Hope this helps.

    Kevin
    Thanks. No idea where Iíd find that issue but Iíll google it

  2. #17
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    Quote Originally Posted by Kevin Gullette View Post
    ......I posted the following on the saubier(small caliber)board.

    As a reference, and a good read, refer to Precision Shooting magazine, May 2001, page 31, "The Real Reason Primers Pierce" by Jerry Stiller.......you know....the guy who designs actions.

    Hope this helps.

    Kevin
    Kevin, that article is great and has the engineering data to back up the small firing pin. Of course Dan is right. It is all futile if your firing pin is a sloppy fit.

  3. #18
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    Lightbulb

    Butch,

    As far as blanking is concerned.....the article points to only the boltface hole diameter, as the primary culprit. I do agree that a good f.p./hole fit is good practice.....but unrelated to blanking.

    This make any sense??

    Anyway......my 2 cents.

    Kevin

  4. #19
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    Quote Originally Posted by Kevin Gullette View Post
    Butch,

    As far as blanking is concerned.....the article points to only the boltface hole diameter, as the primary culprit. I do agree that a good f.p./hole fit is good practice.....but unrelated to blanking.

    This make any sense??

    Anyway......my 2 cents.

    Kevin

    I'm a little confused. I'm of the impression that a .062 firing pin in a fitted hole will prevent blanking. Excess headspace and a weak firing pin spring can contribute to this.

  5. #20
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    Lightbulb Butch........

    Here's some more of my old posting on the small caliber board.

    A little Jerry Stiller math.....

    A 0.082" firing pin probably has an 0.084" boltface hole. The hole is 0.005412 square inches. At 50,000psi, this results in a total shearing force of 277.1 pounds.

    Now use a 0.060" firing pin, with a 0.062" boltface hole. The hole is 0.003019 square inches. At 50,000psi, this gives a total shearing force of 151.0 pounds.

    So.....for a 0.022" reduction in the boltface hole diameter, there is a 45.5 percent reduction in the shearing force.

    As would be expected, a stronger firing pin spring has little effect.........been there, tried that.

    Why these things only seem to happen with small rifle primers AND small calibers????.....I do not know, or can prove........but I strongly suspect that as the sectional density is lowered, a more "focused" pressure spike through the flash hole is created.....and the firing pin is pushed rearward. BUT.......that's just me.

    BTW.....my old 20BR had about the same situation as above. Quite an eye-opening experience. Greg Tannel reduced the firing pin diameter, and bushed the boltface to a smaller firing pin hole size. The result.........with 40gr bullets blanking at 3400fps.........to NO cratering whatsoever at 4150fps.

    Hope this helps.

    Kevin

  6. #21
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    Quote Originally Posted by WSnyder View Post
    Borden method.
    I have always preferred the threaded plug over trying to achieve a press fit that will last forever.

    It is possible to achieve a press fit, but it needs a whole lot more precision.
    And the heating and cooling required for a truly permanent press fit are NOT
    all that good for the heat treat on parts.
    Last edited by brickeyee; 04-02-2020 at 03:21 PM.

  7. #22
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    Quote Originally Posted by brickeyee View Post
    I have always preferred the threaded plug over trying to achieve a press fit that will last forever.

    It is possible to achieve a press fir, but it needs a whole lot more precision.
    And the heating and cooling required for a truly permanent press fit are NOT
    all that good for the heat treat on parts.

    You reckon? Do you have any way to verify this?

  8. #23
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    Green locTite

    Nothing will ever come loose.

    Pete

  9. #24
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    Instead of heating the bolt could you work fast and set the bushing on dry ice and then press fit it or couldnít you work fast enough with that tiny piece? Freeze the ram of the press?

  10. #25
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    Quote Originally Posted by brickeyee View Post
    I have always preferred the threaded plug over trying to achieve a press fit that will last forever.

    It is possible to achieve a press fir, but it needs a whole lot more precision.
    And the heating and cooling required for a truly permanent press fit are NOT
    all that good for the heat treat on parts.
    I donít believe there is any heating involved.
    The original BAT DS actions had a removable piece. Not sure when this changed but I suspect when the bronze bush was also removed from the production units.

    Never seen one move in an early BAT DS action

    Michael

  11. #26
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    Last I knew Kelblyís offered 3 different firing pin diameters custom to fit that bolt . At one time I had 6 Pandas with a combination of different diameters. Even though they had different diameters all bolts head spaced to the same thousand if the bolts were swapped to different actions. But that firing pin had to stay with its original bolt.

    I never could detect any advantage of one pin diameter over the other even on loads with Rl10x that Iím sure went over 75,000#.

    .

  12. #27
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    Quote Originally Posted by WSnyder View Post
    Borden method.
    Screw in is better than trying to anchor by push in.

  13. #28
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    Odessa TX
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    Bushed bolt

    Iíve had a couple Remington bolts bushed by Mike Bryant, fantastic work at very reasonable prices! Plus... pierced primers are a thing of the past for me!

  14. #29
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    Post #25 question

    Michael Huebner- I am not understanding you comment about early BAT DS actions, I have 3 BAT DS actions that have the bronze bushing where the barrel stub screws into the action but do not understand what other bushing? you are speaking of.

    Thanks

  15. #30
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    Feb 2003
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    Melbourne, AUSTRALIA
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    BAT DS - Bolt face bush

    Quote Originally Posted by brcman View Post
    Michael Huebner- I am not understanding you comment about early BAT DS actions, I have 3 BAT DS actions that have the bronze bushing where the barrel stub screws into the action but do not understand what other bushing? you are speaking of.

    Thanks
    The early BAT DS actions have a removable bush in the bolt face.
    If for whatever reason the bolt face or the firing pin hole becomes damaged or you wanted to change the size of you firing pin and need a smaller hole, the existing bush can be pressed out and a new one made with hardened 4140 around 40RC and pressed back in.

    You can check if your bolts have this feature; remove the firing pin assembly and shine a torch or use a bore scope and you will see a dark ring around 1/4Ē in size. It can be pressed out with a 0.1875 punch

    I do have photos of mine, showing the dark ring inside the bolt.

    I hope that clears it up for you

    Michael

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