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Little help with pressure

Discussion in 'Handloading and Reloading' started by allaroundhunter, Jan 31, 2013.

  1. allaroundhunter

    allaroundhunter Well-Known Member

    I was looking through Hodgdon's reloading data center today at different .308 rounds and found something that made me curious.

    I was looking at .308 155 gr loads and found that some of the max loads had pressures in excess of 60,000 psi, while other max loads were under 50,000 psi.

    An example:

    Bullet: 155 GR. SIE HPBT
    Powder: Hodgdon CFE 223
    Bullet Diameter: .308"
    Powder charge: 51.0 grains
    MV: 2966
    Pressure: 60,500 PSI

    Bullet: 155 GR. SIE HPBT
    Poweder: IMR 4007 SSC
    Bullet Diameter: .308"
    Powder Charge: 49.5C
    MV: 2751
    Pressure: 49,900 PSI

    Can anyone explain the differences in MV and pressure to me? And also what the 'C' stands for in the powder charge of the second round?

    Is it due to the CFE 223 being a faster burning powder? What is a "safe" max pressure for a .308?

    Sorry for all of the questions, just trying to get some stuff figured out.
  2. rcmodel

    rcmodel Member in memoriam

    C means a compressed charge, which means they couldn't get any more powder in the case.
    Which means the pressure and velocity were lower.

    Which means IMR 4007 SSC is to slow burning for that caliber / bullet combination.

    SAAMI Max pressure for the .308 is 62,000 PSI.

    Last edited: Jan 31, 2013
  3. allaroundhunter

    allaroundhunter Well-Known Member

    That being the case, would you then say that that is not an ideal powder to use with a .308, rc? It seems as if it is only able to get a 155 gr projectile to 2750 fps that it is not a good powder for shooting at any distance.

    But could it be useful as a reduced recoil load?
  4. rcmodel

    rcmodel Member in memoriam

    No, I would say it isn't an ideal powder for that light of bullet.

    It goes quite well with heavier, 175 grain & up bullets in .308.

    It would be a terrible "reduced load" powder.
    Muzzle blast would be horrendous with lighter bullets and a compressed charge.

  5. allaroundhunter

    allaroundhunter Well-Known Member

    Interesting, thanks for that, rc.

    What would be good recipes for a reduced recoil load?
  6. hueyville

    hueyville Well-Known Member

    Powder choice for reduced.recoil load is on that fills the case 55% to 75% and group well with your bullet. Enough powder for consistent ignition without flashover, light enough charge to be somewhat economical but not a case filler to send sunburn this wasted powder out the muzzle behind the bullet. Your barrel length and bullet selection will cause your powder selection to vary. If it doesn't shoot well though, not much point.
  7. rcmodel

    rcmodel Member in memoriam

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