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Thread: Reloading & temperature

  1. #1

    Reloading & temperature

    The last batch of bullets I made up was a couple of months ago when the temperature was about 10 DegC. In this hot weather (30 DegC) I was wondering if temperature variation makes a difference when reloading, such as resizing brass etc and if this has an impact on accuracy?
    All comments welcome.
    ATB 243 Stalker

  2. #2
    The Coefficient of linear expansion in brass is around 18.7 10-6 m/m / deg K.

    The 20 Dec C (same as K for all practical purposes) temperature difference you quote would result in 20 x 18.7 x
    10-6 mm.

    In round numbers, a 55mm long case would expand in length to 55.0198mm. (.0198mm =
    0.000779in).

    Not enough to worry about IMHO, and probably not measurable given the average reloaders' resources.

    Of course it shrinks back to 55mm at 10 Deg C.


    Last edited by charadam; 17-07-2013 at 15:38.
    "Nonsense! They couldn't hit an elephant at this dista.....................".

  3. #3
    Quote Originally Posted by 243 Stalker View Post
    The last batch of bullets I made up was a couple of months ago when the temperature was about 10 DegC. In this hot weather (30 DegC) I was wondering if temperature variation makes a difference when reloading, such as resizing brass etc and if this has an impact on accuracy?
    All comments welcome.
    ATB 243 Stalker
    your only real concern is if you have a hot [max] load that was worked up in a low ambient temperature using a temperature sensitive powder. Brass expansion etc is of no concern.

  4. #4
    Charadam - thanks for the reply, can rule expansion out.
    Joe - my load is well within the limits so no worries on it being a hot load.

    I am interested in peoples views if temperature deviation has an impact on reloading or if anyone has experience of it.
    ATB 243 Stalker

  5. #5
    Some of the cheaper electronic scales may suffer somewhat from the extremes of temperature.
    (The Unspeakable In Pursuit Of The Uneatable.) " If I can help, I will help!." Former S.A.C.S. member!

  6. #6
    Quote Originally Posted by 243 Stalker View Post
    Charadam - thanks for the reply, can rule expansion out.
    Joe - my load is well within the limits so no worries on it being a hot load.

    I am interested in peoples views if temperature deviation has an impact on reloading or if anyone has experience of it.
    ATB 243 Stalker
    Some powders are affected by the ambient temperature more than others.

    I found Varget is stable/consistent at most temperatures where a change of 15 C can have an impact on Vhit powders.

    I used to run a target load of 60grn V Max at 0.75grn under the max load with N133. I found that it showed pressure signs in hot weather, the POI shifted by over an inch and the groups opened up.
    To resolve the problem but maintain the POI where I wanted it I dropped the charge by 0.5grn in hot weather, which wasn't much but it removed the pressure signs.
    In cold weather the same load shot 0.5inch low, but the groups were excellent.

  7. #7
    Cooter - Thanks for the reply and very interesting as I load N160.
    All comments welcomed.

    ATB 243 Stalker

  8. #8
    Warmer temperatures always affect my reloading.



    Namely, I don't want to sit in the garage and reload in the summer heat, so the heat affects my reloading by encouraging me not to do it!

  9. #9
    Marine - that is exactly why I got no further than resizing this afternoon as the temp in the garage became intolerable and thus the idea for the posting of this thread began.
    ​ATB 243 Stalker

  10. #10
    My reloading room is lovely and cool being under the house and thick stone walls. Only problem is it still needs a heater to keep the damp out. I love Varget for being consistent in temperature changes. I don't have time to be creating new loads for different seasons! Luckily I have quite a few tubs to keep me going.

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