Best way to set COL

Discussion in 'Reloading' started by ru1234, Dec 8, 2006.

  1. ru1234

    ru1234 Member

    Messages:
    22
    Joined:
    Nov 6, 2006
    New to handloading and am loading for my 30-378. There are several different COL's listed in the resources I have consulted. I hear you can customize it for your gun by leaving it long and trying to close the bolt and if it doesn't go, seat it deeper until it just does close. Not sure if that is right or not.
     
  2. royinidaho

    royinidaho Writers Guild

    Messages:
    8,853
    Joined:
    Jan 20, 2004
    Here's what I do.

    Start with a full length sized case with no primer.

    Then cut three slots from mouth to the top of the neck at equal distances around the case mouth with a dremel tool and cutter blade.

    Then completely debur everything and chamfer the case mouth.

    The case mouth should now hold the bullet sufficiently to start it into the case mouth by hand.

    Carefully chamber the dummy round and the leade should seat the bullet giving you the overall length that just touches the rifling with out jamming.

    After removing the dummy cartridge from the chamber back off a bunch on the seating die and insert the dummy into the die. Run the ram up as far as you are going to then CAREFULLY run the seater screw adjustment down until it just touches the bullet.

    Finally seat a bullet in an unprimed full length sized case to use as a standard.

    HTH
     

  3. BountyHunter

    BountyHunter Writers Guild

    Messages:
    4,803
    Joined:
    Jun 13, 2007
    RU

    the method you described can work but it normally gives you about .020-.050 bullet into the lands. That is normally what is called the "jam"

    If the gun has a magazine and you want to use it, then the mag length will determine COL.

    www.sinclairintl.com has a seating depth tool for under $30 that allows you to accurately measure exactly where a particular bullet touches the lands. That way you can determine what seating depth your gun likes as far as on or off the lands.

    Depending on the exact bullet you are using, you may have to adjust your COL (if shooting single shot) to the desired point. Not all bullets are the same length from the ogive to bullet tip.

    BH
     
  4. ru1234

    ru1234 Member

    Messages:
    22
    Joined:
    Nov 6, 2006
    Thanks to both of you for the informaiton.
     
  5. shawn68

    shawn68 Well-Known Member

    Messages:
    64
    Joined:
    Nov 26, 2006
    I do the dummy round with the dremmel cuts. It works great. I just back off my seating die .05. After I shoot some at that depth, I play with them till I find the happy spot.
     
  6. Buffalobob

    Buffalobob Writers Guild

    Messages:
    5,085
    Joined:
    Jun 12, 2001
    The 30-378Wby will have about 0.375 inches of freebore, I beleive. You should double check that number. You may not be able to reach the lands.
     
  7. swebb38

    swebb38 Well-Known Member

    Messages:
    74
    Joined:
    Nov 30, 2006
    Old school way was to take a candle to a dummy rnd and black the bullet with the smoke, then push the dummy in. If it is seated to far it will show where it touches the lands.
    If this is a bad way of doing this, will someone correct me?
    Thanks
     
  8. SamSpade

    SamSpade Well-Known Member

    Messages:
    225
    Joined:
    Sep 21, 2004
  9. markwinwood

    markwinwood New Member

    Messages:
    2
    Joined:
    Nov 2, 2006
    use your neck sizing die to just kiss your fired case.
    you will need to find the sweet spot to have just the right
    grip on the bullet. seat a bullet with fingers and make sure it is concentricit and sticking out. place in chamber adn close bolt real slow, open and measure, best way i know how to find COL.
     
  10. ru1234

    ru1234 Member

    Messages:
    22
    Joined:
    Nov 6, 2006
    Thanks for all the help guys!!