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Thread: Stiff bolt closing

  1. #16
    Join Date
    Nov 2006
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    Augusta, Maine & Palm Coast, Fl
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    6,246

    I spent a few hours

    correcting a huge " cocking on closing " issue with a 700 Rem action I have. what I did was file the cocking piece until the bolt closed without much pressure. The bolt worked great but the rifle would not fire. Pondered the situation for a day and then went looking for the reason. The fireing pin still had plenty of fall I thought so I measured the firing pin protrusion, .050". That seemed light to me so I faced .005" off the face of the place that contacts the inside of the bolt and the rifle fires perfectly. As I was filing the cocking piece I kept comparing the bolt throw and feel to a custom clone I have until I got it to approximately the same as the custom. Works great. I've won two matches with the rifle since. I bought one of those Jewel triggers that has the built in bolt release and is that dern thing slick or what?!!

    Pete

  2. #17
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    Feb 2003
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    Fbks,Alaska
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    Quote Originally Posted by Bob1949 View Post
    Your pin drop does seem a little large.
    Take the bolt out of the action, drop the pin and measure the distance the pin extends from the back of the bolt #A. (-.215")
    Now insert the bolt into the action and push the handle down to lock. (battery)
    Now measure the pin distance again #B. (+.045")
    Subtract #A from #B and that’s your pin drop. (????)
    My Remington 40-X measures 0.220”.

    Bob

    sample measurements in bold type from unmolested Rem 700.

    Increasing travel by cock on close/striker to sear hand off is subtracted?

  3. #18
    Join Date
    Mar 2017
    Location
    Westchester NY and Delray FL
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    134
    If your 40-X looks like this one
    Take measurement #A
    Put the bolt back into the gun and into battery.
    Take measurement #B
    Subtract #A from #B
    The result is the firing pin drop, the amount of movement it makes to get to the primer.

    Bob
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  4. #19
    Join Date
    Feb 2003
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    Fbks,Alaska
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    Quote Originally Posted by Bob1949 View Post
    If your 40-X looks like this one
    Take measurement #A
    Put the bolt back into the gun and into battery.
    Take measurement #B
    Subtract #A from #B
    The result is the firing pin drop, the amount of movement it makes to get to the primer.

    Bob

    Early short shroud f/pin assy pictured.

    Measure total firing pin fall not striker to sear hand off.

  5. #20
    Join Date
    Nov 2006
    Location
    Augusta, Maine & Palm Coast, Fl
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    Quote Originally Posted by Dans40X View Post
    A Remington pin fall is approximately 1/4" & is cock on open & cock on close....until it's corrected.

    Drilling a 3/32" cross pin hole & parting off the aft end of said firing pin is elementary to increase pin fall if/when striker to sear hand off is accomplished.....correctly.


    So, the bolt I've been working on has .220" -.010" 0r .0210" I think. So, is .250" the right amount of fall? My other 700 has .187" of pin fall. Appears it could use some more? So, measure forward from the existing pin hole the amount to get to .250 and drill another cross hole and part that amount off the rear of the pin?

    Thanks,

    Pete
    Last edited by Pete Wass; 11-07-2020 at 05:26 PM.

  6. #21
    Join Date
    Feb 2003
    Location
    Fbks,Alaska
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    Quote Originally Posted by Pete Wass View Post
    So, the bolt I've been working on has .220" -.010" 0r .0210" I think. So, is .250" the right amount of fall? My other 700 has .187" of pin fall. Appears it could use some more? So, measure forward from the existing pin hole the amount to get to .250 and drill another cross hole and part that amount off the rear of the pin?

    Thanks,

    Pete

    3/16" total pin fall?
    (someone's been hacking)

    Install another OEM striker/cocking piece & measure the outcome.

    Once you shorten the aft end of the pin & drill another cross pin hole you will have other issues to contend with since the striker/cocking piece will hit the bottom of the firing pin cocking cam/helical surface in the bolt body.

    The cocking/striker finger can/should not hit the cam/helical surface in the bolt body at 6oclock position in the bolt body.

  7. #22
    Join Date
    Feb 2003
    Location
    Fresno
    Posts
    5,562
    I don't know why anyone has any issue measuring firing pin fall on a 700. If you take all measurements with the trigger in, and the bolt closed, all you have to do is measure from the back of the cocking piece to the back of the shroud. If the cocking piece sticks out of the back of the shroud when the action is cocked, you measure that, and add how far it sticks out to how far down in the shroud it is after the action is fired, chamber empty.

    On the protrusion, I think that there was something else going on, because .050 should be plenty to fire the rifle. I say this because a retired engineer from Savage, Bob Greenleaf, once told me that he set his personal Savages for .035. Although there have been changes recently, at that time all of their long and short CF actions had adjustable protrusion.

    Cock on close happens as the bolt handle is turned down, after the cocking on opening has taken place. The complication is that the back of the shroud moves as the handle is turned down because of the threaded connection to the bolt body. Fortunately we can calculate this change. The shroud thread is 1/2-13 so on a RH action the shroud moves to the rear (1/13)/4" one divided by 13, that answer divided by four). This works out to .019" . Measure where the back of the cocking piece is relative to the back of the shroud, with the bolt held forward but before it is turned down, then take the same measurement after turning the bolt down and on a RH action add .019". For a LH action subtract that amount. For a stock RH 700 SA that I just measured, bolt forward after cocking on opening the cocking piece sticks out of the shroud .009. After turning the handle down the same measurement is .049. Subtracting one from the other and adding .019 gives .059 cock on close.

  8. #23
    Join Date
    Nov 2006
    Location
    Augusta, Maine & Palm Coast, Fl
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    6,246

    What I had

    Quote Originally Posted by Boyd Allen View Post
    I don't know why anyone has any issue measuring firing pin fall on a 700. If you take all measurements with the trigger in, and the bolt closed, all you have to do is measure from the back of the cocking piece to the back of the shroud. If the cocking piece sticks out of the back of the shroud when the action is cocked, you measure that, and add how far it sticks out to how far down in the shroud it is after the action is fired, chamber empty.

    On the protrusion, I think that there was something else going on, because .050 should be plenty to fire the rifle. I say this because a retired engineer from Savage, Bob Greenleaf, once told me that he set his personal Savages for .035. Although there have been changes recently, at that time all of their long and short CF actions had adjustable protrusion.

    Cock on close happens as the bolt handle is turned down, after the cocking on opening has taken place. The complication is that the back of the shroud moves as the handle is turned down because of the threaded connection to the bolt body. Fortunately we can calculate this change. The shroud thread is 1/2-13 so on a RH action the shroud moves to the rear (1/13)/4" one divided by 13, that answer divided by four). This works out to .019" . Measure where the back of the cocking piece is relative to the back of the shroud, with the bolt held forward but before it is turned down, then take the same measurement after turning the bolt down and on a RH action add .019". For a LH action subtract that amount. For a stock RH 700 SA that I just measured, bolt forward after cocking on opening the cocking piece sticks out of the shroud .009. After turning the handle down the same measurement is .049. Subtracting one from the other and adding .019 gives .059 cock on close.
    was .050" of pin protrusion would not ignite a primer so I extended the protrusion by .005" and it works fine now. I guess I'd better let sleeping dogs lie at this point. Measuring isn't an issue for me but I was looking to have the right amount of pin fall. If there are going to be several issues to deal with I guess as long as the rifles go bang, I'll leave then be.

    Pete

  9. #24
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    Feb 2003
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    Fresno
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    5,562
    If it ain't broke....

  10. #25
    Join Date
    Nov 2006
    Location
    Augusta, Maine & Palm Coast, Fl
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    6,246

    Wellll,

    The short pin fall in the older 700 didn't make sense so I took the whole pin mechanism apart and found the pin is an hybrid Aluminum "Speed Pin" and the cocking piece black in color, not the shiny i'm familiar with. So I gets to measuring things. The Speed Pin is not the same length as the stock pin where it matters in pin fall, longer, so giving less pin fall. I happened to have a stock pin so puts eh with a stock cocking piece I happened to have in stock and tries er again. Whadda ya know, now I have .211" of pin fall. Life is good ain't it? Wouldn't ya think someone making "Speed Parts" would at least make em the same length as the original? Perhaps a shorter fall seem more desirable to the Speed Pin maker but I am not convinced.

    Pete
    Last edited by Pete Wass; 11-09-2020 at 05:08 PM.

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