Bullet-neck bearing surface & pressures?

Discussion in 'Reloading' started by boscodog, Jul 29, 2015.

  1. boscodog

    boscodog Well-Known Member

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    Mar 9, 2012
    I’d like some help with a few questions -

    I had a 338/300 “edge built that I want to use as a hunting rifle so I made it a repeater, OAL is 3.830 to the lands.

    Using 300 grn bergers, seating the bullet .020th off the lands I have approximately .500 of bullet in the case and about .235 extra bullet bearing surface. I was told that seating a bullet with the least amount in the case and still having full neck bearing surface is best for accuracy, is this true? What if any are the advantages or dis-advantages?

    I also have another question - Will I be able to get the same speeds using less powder than a bullet that is seated further out? My thinking is that the pressure will be greater.

    Thank you,
    Tom
     
  2. Mikecr

    Mikecr Well-Known Member

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    Aug 10, 2003
    Seating bullet bearing into neck-shoulder junction is not 'good' for accuracy.
    It creates a lot of neck tension variance, which affects velocity spreads & tune.

    Personally, this is just me, I'd get it throated longer and convert to single shot if I couldn't get a better size mag.
     
  3. J E Custom

    J E Custom Well-Known Member

    Messages:
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    Jul 29, 2004

    It has always been considered ideal to seat the bullet at the base of the neck or the body of a boat tailed bullet at the base of the neck (The boat tail part of the bullet would infringe on the powder capacity of the cartridge. It has not been proven that this condition was detrimental to accuracy, just powder capacity.

    To me, a round that fits the magazine is more important for hunting than single loading. With proper
    case prep and good loading practice seating deep should not be a problem for accuracy.

    On the velocity question, Pressure = equals velocity, so with less powder and faster powders you should be able to match the velocity because with more seating length off the lands you sometimes get more volume from the same powder charge.

    Work up the load that the rifle likes the best at the length you want and all will be fine.

    Just my opinion

    J E CUSTOM