300 wby bullet seating depth question

Discussion in 'Reloading' started by axe3761, Apr 5, 2012.

  1. axe3761

    axe3761 Member

    Dec 24, 2008
    hi all. i am working up a load for my 300 wby. it has a custom heavy barrel and is 30 inches long. left hand action mark v. my question is i am measuring max coal from bullet touching lands to base of cartridge. i have come up with a cartridge length of 3.850'' now if i seat the bullet 20 thou deeper to start i am left with a cartridge that is 3.830'' long. factory ammo is 3.560'' max coal. i made up a dummy round to measure with and when i just start seating the bullet into the case i get a measurement of 4.020'' i am left with .190'' of the bullet base in the case mouth. is this going to be enough bullet in the case to perform safely or should i seat it deeper and start out with a bigger jump. i read the vld seating thread and it answered a few questions but am a little sketchy on this one. i am using 220 gr sierra matchking bthp's cause i have lots of em. lol. i have not a clue if this barrel has the weatherby freebore or not but am thinking it does because the coal is so long even with these long bullets. not worried about fitting a magazine, only need one shot. thanks for any help.

    if i give it one bullet diameter i already have a .130 thou jump to start give or take.
    Last edited: Apr 5, 2012
  2. LRSickle

    LRSickle Well-Known Member

    Jun 8, 2009
    A general rule is to seat your bullet at least a caliber's depth into your neck. In other words seat your .308 caliber bullet .308" deep as a minimum. On my Weatherbys I start there and work back.
    I know about the freebore thing and Weatherbys. With my 300Wby, my 150s plop out of the modified case and lays in the leade before it touches the lands.

  3. boomtube

    boomtube Well-Known Member

    Oct 8, 2007
    A lot of cases don't have a neck one caliber long.

    No matter what any of us may tell you, any experienced reloader knows you're going to have to work with your own rifle to learn what bullet jump does best and using a left or right handed action won't change a thing.