Temperature and load development 7mm rum

Discussion in 'Reloading' started by hunt7112, Dec 10, 2010.

  1. hunt7112

    hunt7112 Member

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    Dec 10, 2010
    New to the site but always on hear reading the good info.
    I now have a question for anyone who could help. I live down in south central AZ where it is usually hot year round. I developed my 7mm RUM load in august and early september trying to catch the cooler times of the day if I was lucky it would be 87 to 90 degrees.

    My load is 86 gn of IMR7828 with federal 215 and 150 scirocco I averaged 3360 fps

    I shot the other day in temps of 65-67 degrees is it normal to lose 130fps in cooler temps, and would I be better off developing my load at closer temps to what we would most likely see during our fall hunts.

    Thanks for any info.
     
  2. ReachnOut

    ReachnOut Well-Known Member

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    Dec 6, 2010
    Your velocity drop is not unusual with the 30+ degree drop in temperature due to the significant rise in air density with the cooler temps. I shoot in far ranging temps and don't adjust my sight in for a specific change other than being aware of the loss or gain and mentally making he adjustment. Under a couple of hundred yards, you probably wouldn't notice a significant change in the point of impact. Over 500 you need to start paying attention.
     
  3. hunt7112

    hunt7112 Member

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    Dec 10, 2010
    Thanks for your reply, and I found tons more info above. Should have searched a little more from the beginning.
     
  4. LRSickle

    LRSickle Well-Known Member

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    Jun 8, 2009
    Rl22 is another powder that is temperuture sensitive. A time to be cautious is when your shooting a load that's close to max. If you take it out in hot weather you might have some problems.