Jamming into lands

Discussion in 'Reloading' started by Okiecat, Jan 27, 2007.

  1. Okiecat

    Okiecat Well-Known Member

    Messages:
    50
    Joined:
    May 3, 2005
    Dumb question. How do you determine that you are .005 or .010 jammed into the lands with the bullet. I have a stoney pt oal and a sinclair nut and calipers. I can't figure how once you touch the rifling how do you get a measurement of the jam. Thanks
     
  2. Eaglet

    Eaglet Well-Known Member

    Messages:
    2,779
    Joined:
    Feb 2, 2005
    Okiecat,
    There is no such a thing as a dumb question.
    Hopefully I'm understanding the question correctly. Once you
    touch the rifling, and you measure this many times to make
    sure you're getting the same dimension, you write it down on
    paper; let's say you measured 3.662" to just touching the rifling. Now if you want to be 0.010" into the rifling we
    add 3.662" + 0.010" = 3.672" this new number is what you
    want to have when you sit the bullet into the casing. you
    would have to adjust your bullet sitting die until your AOL
    is 3.672".
    I hope I answered the question.
     

  3. Ballistic64

    Ballistic64 Well-Known Member

    Messages:
    669
    Joined:
    Dec 21, 2004
    You can do the procedure eaglet describes,but depending on your neck tension/quality of brass,you may never actually get .010 into the lands.Just remember if this is a hunting gun and you seat this way,you may not be able to extract a live round without the bullet sticking in the throat and dumping powder all over.
     
  4. Chawlston

    Chawlston Guest

    [ QUOTE ]
    Okiecat,
    There is no such a thing as a dumb question.
    Hopefully I'm understanding the question correctly. Once you
    touch the rifling, and you measure this many times to make
    sure you're getting the same dimension, you write it down on
    paper; let's say you measured 3.662" to just touching the rifling. Now if you want to be 0.010" into the rifling we
    add 3.662" + 0.010" = 3.672" this new number is what you
    want to have when you sit the bullet into the casing. you
    would have to adjust your bullet sitting die until your AOL
    is 3.672".
    I hope I answered the question.

    [/ QUOTE ]

    OAL can differ depending on the types of bullets you use with a constant seating depth. For instance if you are using a polycarbonate tipped bullet, the tips vary in dimension from lot to lot. Even non-poly tipped bullets vary in the distance from the bullet ogive to the bullet tip and that will give you erroneous depths for the same readings of OAL. To truly get an accurate loading specific distances off or into the lands, you will have to get an ogive tool for measuring seating depth. Sinclair has two models of them. Once you start using them, you will see which company really makes the most constistant bullets.

    James
     
  5. Okiecat

    Okiecat Well-Known Member

    Messages:
    50
    Joined:
    May 3, 2005
    Wow, thanks for the tutorial. That was so simple. I got it. I am using the Sinclair Nut and understand that part of the ogive dimension. Now back to the bench.