Temp sensitivity of powders

Discussion in 'Reloading' started by The Oregonian, Jul 24, 2018.

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  1. The Oregonian

    The Oregonian Well-Known Member

    Jul 20, 2012
    It is hot as hell in Tennessee in the summer...can I get a good idea of how this load will vary in velocity in colder weather by putting loaded rounds in freezer prior to shooting? Will that give me a good idea, some idea, or no idea (bc maybe the rifle steel has to be cold as well, or some other reason)?

    Obviously will test as the weather cools down but hoping to get an idea at this point.
  2. bigedp51

    bigedp51 Well-Known Member

    Dec 10, 2010
    The number below to the right of the type powder is the fps change for each degree of temp change.
    The single base Hodgdon's Extreme Powders are the least sensitive to temp change.
    Example of double and single base powders, the military switched from RL15 to IMR-4064 in their 7.62 long range sniper ammunition. This was due to the temp extremes in Iraq and Afghanistan.

    Click on the image below to enlarge.

    calib likes this.
  3. ShtrRdy

    ShtrRdy Well-Known Member

    Jan 14, 2012
    It will give you some information. A friggin cold barrel will be slightly smaller diameter so that will increase pressure a bit.