Bearing Surface, Pressure and Velocity

Discussion in 'Reloading' started by 270 MKV, Sep 24, 2012.

  1. 270 MKV

    270 MKV Well-Known Member

    Aug 21, 2012
    so, I was thinking the other day..what effect does bearing surface have on pressure and velocity...

    Reason being...I have three bullets I am working with...

    the lightest one has the longest bearing surface....hmmmm

    so, was wondering....

    if a heavy bullet has a shorter bearing surface than a lighter bullet...what would that do to the possible load...could it indeed be loaded to a similar powder charge as the lighter bullet??

    Final velocity would of course be lower...but what would peak chamber pressure do???
  2. bobnob

    bobnob New Member

    May 4, 2012
    Good question! I guess all the variables need to be calculated of course. It would depend in part on the differences in the friction bearing area and weight difference.

    I can't call on much relevant experience to help except the following; Once when I was working up loads for a 270 I was experimenting with 130, 140 and 150g bullets, and all three weights were of different brands. I used identical charges - 59g - of AR2213/H4831. In the case of all three different bullets the speed was a near identical average of 2970fps with a near identical point of impact.

    Not directly relevant to your query but relative somewhere on the periphery.