Temperature affect on muzzle velocity (IMR4831)

Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by TX mountain hunter, Dec 18, 2012.

  1. TX mountain hunter

    TX mountain hunter Well-Known Member

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    Dec 17, 2010
    I'm currently seeing 3460 fps with my 6.5-280AI & 110 grain bullet, at 65*F. I plan on going on a hunt in a couple weeks where the temperature is going to be in the 10-20*F range. I have no way to test my rifle / load in these conditions. Since IMR 4831 is supposedly not temperature stable, what kind of muzzle velocity drop should I expect to see? I would prefer to be able to keep the gun loaded at all times for the possibility of a quick shot (ruling out the load in the pocket idea).
    Thanks.
     
  2. dig

    dig Well-Known Member

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    4831 is very stable. I shoot often in 100 plus degree tempratures and notice about 60 fps difference in 40 degree temps. I have been using 10 fps for every 10 degrees in my balistics programs which is working well. This is not science just a rule of thumb I have used over the years. I will say there is more of a drop at the extremes from say 110 degrees to 80 degrees. At those low temps you are going to have to experiment a bit. Best of luck.
     

  3. TX mountain hunter

    TX mountain hunter Well-Known Member

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    Dec 17, 2010
    Are you referring to IMR or H 4831? 10 fps per 10 *F sounds reasonable enough to me..
     
  4. dig

    dig Well-Known Member

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    IMR, currently switching to H4831sc though, meters better.