long throat in 300 mag

Discussion in 'Reloading' started by bigsal5353, Aug 25, 2008.

  1. bigsal5353

    bigsal5353 Well-Known Member

    Mar 4, 2004
    I'm shooting a remmy 700p 300 mag with 190 gr HPBT's. I started working on my OAL. When I use the Hornady OAL gauge to measure how far out I have to seat my bullet to hit the lands, I get 4.133"( base to ogive) which puts the 190 matchking flush with the case neck. I obvioulsy cant seat my bullet to be close to the lands, right? How much of the bullet should I have in the case neck (some say if doesnt matter, and others have said I should have the neck of the case filled with the bullet)? should I switch to a heavier/longer bullet 220's?
  2. royinidaho

    royinidaho Writers Guild

    Jan 20, 2004
    A guideline I came across many years ago was that at least 1 caliber should be in the neck.

    I took that one step further and resized only a little more than one caliber of the neck.

    It seemed to work well over a period of years w/a 270 Win.

    I don't know if this is generally accepted practice, but it's what I do.

  3. MagnumManiac

    MagnumManiac Well-Known Member

    Feb 25, 2008
    If your rifle is a repeater, I would load to the magazine length and not worry about how far your bullets are from the lands. There's not much you can do about it. Shoot it at that length, and see how good the accuracy is before you worry about seating into or just off the lands.
    Once you have an accurate load you can tune your rifle to shoot that load even more accurately.

    If you are going to shoot it single shot, seat them out as far as the bottom of the neck, this will give ample bullet pull for single loading.
    All Weatherby rifles/cartridges have 'freebore' and they are very accurate with tuned loads and rifles.

    The only other option is to re-barrel with a 'match' chamber cut into it.

  4. johnnyk

    johnnyk Well-Known Member

    Dec 24, 2001
    I use 1/2 caliber in the neck (.154") for short bullets or long throats...as long as the runout doesn't get to bad.
    Instead of re-barreling, you could have a .25-.50" trimmed off the barrel threads and have it re-chambered with a match chamber.
    I have a 700P in 7mmRM and it seems to have a normal to short throat. JohnnyK.
  5. kraky2

    kraky2 Well-Known Member

    Jan 6, 2005
    My Tikka also has a very long throat yet is extremely accurate at magazine length which is 3.350. I can't help but wonder if manufacurers are dialing in the equivalent of wby freebore to some of these rifles so some of these "magnum" and heavy magnum loads don't become a problem.