Bolt Jump

Discussion in 'Gunsmithing' started by sdriverbottom, Aug 27, 2013.

  1. sdriverbottom

    sdriverbottom Well-Known Member

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    Feb 26, 2011
    While dry firing I notice the bolt jumps upward. As well as the bolt jumping my crosshairs on only some dry fires jump as well (probably a form issue) ..are both these corillated together with the firing pin? Or what? I have search for others on this issue and found some say its big deal others say its normal, and I can't tell you If the bolt jumps when a live round is fired. I just want to know if any accuracy is effect by the bolt jump. Gun is remington sendero 300rum with a Jewell trigger.
     
    Last edited: Aug 27, 2013
  2. MTBULLET

    MTBULLET Well-Known Member

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    it probably won't so it with a snap cap or dummy round in chamber
     

  3. sdriverbottom

    sdriverbottom Well-Known Member

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    Might have to try the dummy round and see what happens this evenin
     
  4. ultraedge

    ultraedge Well-Known Member

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    I have seven customs built on l.a. Remington 700 actions. Four of these originally were Senderos in .300ultra just as you described. I had trouble with several not grouping unless I held them a certain way. I discovered that when dry firing those that gave trouble, the crosshair would jump. The group that shot well with a light hold, when dry fired , did not show any crosshair movement. I experimented with changing the firing pin and spring assembly until I got rid of the jump. Now all of the rifles group well using a light hold.
    On another note, some of these firing pin and spring assemblies were j-lock type and some were not. I could not tell any accuracy difference between the two. Gary
     
  5. sdriverbottom

    sdriverbottom Well-Known Member

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    Well I stuck a dummy round in and pulled a couple. The bolt just ever so slightly moved. I then got behind the gun to see crosshair movement and there was none..not sure if I should look at replacing the firing pin and spring or just buy some snap caps for dry fire practice now. Thanks!
     
  6. J E Custom

    J E Custom Well-Known Member

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    The reason the bolt jumps is that there is to much head space without any round in the chamber.

    There has to be bolt clearance in the bolt recess and the bolt nose to breach.

    Thy a fired case in it as MTBULLET suggested and it probably wont move very much if any.

    J E CUSTOM