temperature to velocity variation input

Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by scott, Jul 1, 2006.

  1. scott

    scott Member

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    Anyone have any info on temperature variation with different powders..

    Example, a 243, 6mm, 257, 25-06, 270,7mm 30-06, 300's etc using Re-19-22-25 or IMR-4831 4350 etc
    from a cold 20-25 deg day (what vel do you get?), on up to 60-70 deg (what vel do you get now).

    I have not done enough testing myself to make anything yet, I'd like to know how ball powders compare to stick powders from 20-70 deg or something around that. have any of you have done any temperature to velocity testing?

    scott
     
  2. royinidaho

    royinidaho Writers Guild

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    58.9gr RL-22 270Win 27" bbl = 3200 FPS on 70/80 degree summer day. When in 90s, don't shoot that load.

    Same load in fall/winter @ about freezing is 130 FPS less.
     

  3. davewilson

    davewilson Well-Known Member

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    i think most concentrate on how much extra powder they need to get the same velocity when it's cold rather than how much slower it is.
     
  4. royinidaho

    royinidaho Writers Guild

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    [ QUOTE ]
    i think most concentrate on how much extra powder they need to get the same velocity when it's cold rather than how much slower it is.

    [/ QUOTE ]

    Dave,

    I do that also. This was an unintended discovery. I 'just happened' to shoot over the chrono on a very cool day for no good reason at all. I was suprised that the velocity difference was that large. Still shot good though. But needed a new drop chart for cool weather shooting. I'm not trustworthy enough to keep a load for each season. /ubbthreads/images/graemlins/frown.gif
     
  5. brianwinzor

    brianwinzor Well-Known Member

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    Scott, I have numerous examples of temperature variation that I could use, but here is one example and I will look up records for others.
    Example 1
    25/06 AI Rem Case, Fed 215 Primer, Nosler 100 grn SPBT LL 3.180 Load 60.5 grains IMR 4831

    01/06/1988 - Temp 11C (52F) - 3,554 FPS (3 shot group)
    01/07/1988 - Temp 15C (59F) - 3,589 FPS (3 shot group)
    20/03/1989 - Temp 28C (83F) - 3,673 FPS (15 shots 3 groups)
    19/05/1990 - Temp 14C (57F) - 3,547 FPS (3 shot group)

    My experience is that all powders that I have tested seem to increase in velocity as temperature increases. Although some may rise more than others. Regards, Brian
     
  6. davewilson

    davewilson Well-Known Member

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    Brian,not on subject but why are you using a 215 primer with that case? i'll bet you'd get a better ES and downrange accuracy with a milder primer.
     
  7. brianwinzor

    brianwinzor Well-Known Member

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    Dave, That test was done 18 years ago, when my gunsmith recommended me to use magnum primers. I still use magnum primers whenever I am using ball powders, and especially when I am using H870. However, I have been using the Rem 91/2M primer recently and that does seem to be milder than the Fed 215.

    I will take up your suggestion and do a test of a standard V magnum primers in my 25/06AI, and see what the results are. Regards, Brian.
     
  8. scott

    scott Member

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    Thank you Roy.. That is one result I was looking for, 130 fps dif from 30 to 75 deg..

    I would now like to know what ball powders will do under the same loadings or a simular round.

    are we talking 200 to 300 fps or maybe up to 500 fps differance with ball powders or what?

    thanks

    scott