Varget Temp Stability

Discussion in 'Competition Forum (All Calibers)' started by karrarararararar, Feb 19, 2019.

  1. karrarararararar

    karrarararararar

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    Hey all,

    Thought I'd share a bit of interesting data from the other day. Temperature stability is often talked about with choosing powders and Varget is often touted as being really temperature stable. I decided to run a few rounds of my 600 yard service rifle load across the chronograph on a chilly ND afternoon last week. This load is 22.6 grains of Varget in Starline brass with an 80 grain Hornady ELD-M. I originally chrono'd this load on August 12th, 2018 in Moffit, ND when it was ~100 degrees ambient at 2719 fps. This same load chrono'd 2700 fps in -2 degrees ambient for a whopping loss of 19 fps or .69%. Pretty temperature stable if you ask me.
     
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  2. ShootDots

    ShootDots Gold $$ Contributor

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    QUESTION: Is the load you are using have a large window where maybe 2 tenths up and 1 or 2 tenths down in charge weight make very little difference in velocity or accuracy?
     
  3. Rushty

    Rushty Silver $$ Contributor

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    Your extra speed may be a result of different air density from different temperatures affecting the bullet in flight rather than the powders stability..
     
    Last edited: Feb 23, 2019
  4. Terry

    Terry Gold $$ Contributor

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    Do you have any 60 - 90 degree data?
     
  5. johara1

    johara1

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    Are you using the same lot of powder? jim
     
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  6. dmoran

    dmoran Donovan Moran Silver $$ Contributor

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    Looked back through my "sensitivity tests" that I conducted over the years.
    Five of them included Varget, with an average of: 0.41-fps per 1-degree
     
    Last edited: Feb 21, 2019
  7. arm017

    arm017

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    I'd be interested in some of your other numbers too?
     
  8. BenPerfected

    BenPerfected Gold $$ Contributor

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    Thought....does the temp of the loaded round have any impact on FPS consistency?
    Ben
     
  9. karrarararararar

    karrarararararar

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    I haven't tested it with higher or lower charge weights, but have shot it once with thrown charges and saw the same accuracy.

    I haven't had a chance to test at those temps and we wont see 60 degrees here until May

    Same jug of powder.
     
  10. david kieffer

    david kieffer Gold $$ Contributor

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    oh yes ; big time . let your ammo set out in the sun ,or let a round in a hot chamber a few minutes ,and see what happens . dependent on powder can be bad bad ,pressure spikes will happen. thanks. dave
     
  11. ShootDots

    ShootDots Gold $$ Contributor

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    Many times, if you have a fairly W-I-D-E "window", (with a "smallish" cartridge like a 6 Dasher or a 6.5 x 47) where the velocity and accuracy does not change hardly at all, generally you will not experience large swings in velocity due to temp change. And a wide window with small cartridges is only a few tenths! EXAMPLE: a few years ago I was running a 7 SAUM with 180 Hybrids. I had a window, with RL-23, from 61.0 to 61.5 (which is a good window for a fairly large cartridge) where the velocity hardly changed and the point of impact was the same (at 300 yards anyway) and the accuracy never changed. I ran that load, 61.3, from the low 40 degrees here in Arizona to a day I remember was 112 with no ill effects on accuracy! Having a fairly wide accuracy window, coupled with a temp stable powder occupies the best of both worlds!
     
    Last edited: Feb 20, 2019
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  12. DirtySteve

    DirtySteve Gold $$ Contributor

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  13. BenPerfected

    BenPerfected Gold $$ Contributor

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  14. onelastshot

    onelastshot Gold $$ Contributor

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    Varget is one of my go to powders, I just received another 8 pound container of it yesterday. My 338 Federal loves it. 46 grains of Varget, 213 grain Hammer bullets and I'm good to go. Using this recipe in Africa this fall. Perfect for my 338 Federal.
     
  15. Meangreen

    Meangreen

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    This mirrors my results almost exactly.

    One caveat: The size of the powder charge itself has something to do with the range of variance.

    308 class cartridges typically show an average variance of about 0.5 fps per degree. 30-06 class show around 0.7 fps per degree. Cartridges in the neighborhood of 300 Winmag and larger have an average change of 1 fps per degree, regardless of powder used. The 50 BMG regularly has a variance over 2 fps per degree.

    The other thing about temp stability has to do with marketing. Powders like Varget and H4350 are made to light easier at low temps, and therefore show less variance from say 0 - 70 degrees. This lowers the average so that companies can honestly tout the "temp stable" aspect.

    When temps get over about 80 degrees, ALL powders become temp sensitive to differing degrees.
     
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  16. Ned Ludd

    Ned Ludd Gold $$ Contributor

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    Not typically in a case the size of a .223 Rem. I'm lucky to see more than a 0.2 gr wide window in those small cases.

    I also gathered some recent temperature/velocity data with an established Varget load (.308 Win/168 Hybrids/Fed205/Lapua Palma brass). Avg MV at 93.5 degrees F was 2910 fps, avg MV at 51.5 degrees F (i.e. delta = 42 degrees F) was 2893 fps. The predicted change in velocity per degree F is 0.405 fps/degree F, which rounds to the exact same value Donovan reported above, 0.41 fps per degree.
     
    Last edited: Feb 20, 2019
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  17. Marksman63

    Marksman63

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    How you guys compare Varget with VV-N140? Can it substitute Varget in terms of temp stability?
     

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