loading for the temperature

Discussion in 'Reloading' started by jmason, Sep 28, 2008.

  1. jmason

    jmason Well-Known Member

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    If you find a load your gun shoots well, and it's warmer than it will be in hunting season would you use a powder charge that's at the high end of the node in anticiption of cooler temps?
     
  2. Boss Hoss

    Boss Hoss Well-Known Member

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    Depending on the rifle and powder I do it all of the time BUT the chrono is the way you can tell what is really going on. There is no free lunch so to speak. Never have I had a load that shot at a higher velocity on a colder day.

    A possible issue is the 1st shot thru a clean tube--higher pressure possibly and with factory tubes most likely a different POI. Just something to keep in mind..
     

  3. royinidaho

    royinidaho Writers Guild

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    RL-22 in 270 Win. - 130 FPS velocity reduction from 70* summer temp to teens in winter.

    With powders such as IMR 7828ssc I load to max in less than 70* temps and don't worry about it except in my long range guns where I am a bit more particular.

    When I chrono a given load @ lower temperatures it is always lower than in warmer temps. If it is sufficiently low I enter the lower velocity into the drop chart program and make a new drop chart. I'm not one to have a cold weather load and a warm weather load. I'd invariably get'em mixed up sooner or later.
     
  4. papa45

    papa45 Well-Known Member

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    Ditto.

    Another thought... Reduced velocity at lower temperatures can change more than just trajectory. Barrel harmonics can affect group size and POI. jmason's idea of using a charge that's at the high end of the node sounds like a reasonable approach, but the only way to tell for sure is to test at the anticipated lower temperatures.
     
  5. jmason

    jmason Well-Known Member

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    Thanks guys. I will test it in colder weather for sure. I was just looking for validation of my thought.
     
  6. AJ Peacock

    AJ Peacock Well-Known Member

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    Thats exactly what I do. I figure the lower temps will still keep it in the node.

    AJ
     
  7. royinidaho

    royinidaho Writers Guild

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    I figure that if group size doesn't change with large drops in temperature with 200 yd point of impact being the only change, a tweak up in zero setting being necessary, then the drop chart change is considered based on a downrange point of impact check along with the chrono check.

    There was a thread a while ago, regarding "how wide is your node". That consideration is very important. Node width seems begs for a bit more consideration of the OCW method of load development along with the Ladder method.
     
  8. Boss Hoss

    Boss Hoss Well-Known Member

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    Ditto there old boy Roy!!!!!
     
  9. jmason

    jmason Well-Known Member

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    The way I have been doing load development is to shoot a ladder. If I find what I perceive to be a node I then add and subtract a few grains on the high and low side of the node and shoot confirmations. For example if I thought I had a node at 55.4-55.7 I'll load 55.2, 55.4, 55.6, and 55.8 (or wider) and look for similar velocities and POI shift to find the edges of the node. I then select what is the center of it. I'm going to loose 30+ degrees before rifle season so I figured if I went to the high side of the node (guessing) all would remain well when it gets colder.

    Either way I'll learn the hard way later this fall!

    By the way I authored "How wide are your nodes":)