300 WM Chamber Dimensions

Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by kcebcj, Jan 10, 2014.

  1. kcebcj

    kcebcj Well-Known Member

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    Do any of you gentlemen know the standard SAAMI length bolt face to lands in a 300 WM. Have any of you set a 300 WM barrel for the 215gr Bergers and if so what COAL did you end up with.... bullet just touching the lands?

    Been looking everywhere and only found one number bolt face to the lands and that is 2.9545 but don't know if it is accurate. Thanks in advance.
     
    Last edited: Jan 10, 2014
  2. MagnumManiac

    MagnumManiac Well-Known Member

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    The dimension you quoted is correct, but, it can be +.015" longer than this and still be within spec, although this is not a rule that anybody adheres to. I have a Kimber 8400 in 300WinMag, it's throat measures a whopping .370", even though it's a 'match grade' chamber. I cannot get anywhere near the lands at magazine length, but I have to say that once the sweet spot was found it's a real shooter.
    You can measure to the ogive on a dummy round that fits your mag length and work backwards to determine what throat length is required for your build. This is how I do it.
    If the SAAMI throat length is .2976", cutting a chamber shorter may increase pressure, you just have to figure out what you want to achieve.

    Cheers.
    gun)
     
  3. kcebcj

    kcebcj Well-Known Member

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    Thanks for your response.

    I can get a max COAL with the mag (300 Weatherby Mark V) box of 3.6 and still have them feed properly. So it looks like it would be about .2595 short of getting to the lands using the 215gr Berger (long nose 0.905) and the SAAMI dimensions. If I shortened the throat by the number above that would put the bullet at the lands with a overall COAL of 3.600. I could start working loads with a COAL of 3.590. Ran all this through Quick Load and things look pretty good.

    Any comments?