rifle setup

Discussion in 'Long Range Hunting & Shooting' started by TH, Sep 7, 2009.

  1. TH

    TH Well-Known Member

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    I have ben doing load development all summer long. I finally found a load that shoots great in my rifle. I cronographed my load at 3278 fps at 900 feet of elevation and 60 degreese outside temp. When I go hunting next month base camp will be at 9000feet and hunting in elevations up to 14000 feet. When i imput the information in my sierra program will my load speed stay the same at this elevation. The temp will be colder where im hunting probally around 30 degrees. Im shooting H50bmg powder.
     
  2. liltank

    liltank Well-Known Member

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    What caliber are you shooting? What grain bullet?

    Tank
     

  3. TH

    TH Well-Known Member

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    338 408 300grn smk
     
  4. elkaholic

    elkaholic Well-Known Member

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    30 degree lower temp will probably make around 40 to 50 feet less velocity. You will have to test to make sure as powders vary. Try shooting in warmer weather and chronograph at above 70 degrees and then ice your loads (and chamber/barrel) and note the difference. Also leaving a round chambered very long in a hot chamber will have the same affect i.e. (raise pressure/velocity)
     
  5. trebark

    trebark Well-Known Member

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    Both the temperature change AND the elevation change will affect velocity and your POI.

    Does your ballistic program have a trajectory validation? if so, when you get to your hunting spot, you can verify your trajectory and be good to go.
     
  6. TH

    TH Well-Known Member

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    What would you guys recomend. Take my cronograph with me and shoot a few over before i hunt? I also have a PDA with the nightforce program. So i can adjust my drop charts my biggest concern was change in velocity.
     
  7. AJ Peacock

    AJ Peacock Well-Known Member

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    Just ice your ammo and take a cold bore shot over a chrono. This will get you awful close. The elevation will not change your muzzle velocity, just the temperature. Let your rifle cool for 30 minutes then take another shot with the iced ammo. As was said earlier, you'll probably get 30-50fps less.

    I hunt with a 338Allen Magnum and use 3270fps as my velocity, the JBM Litz data for the 300smk works VERY well for my drops up to and past 1200yds.

    AJ
     
  8. jmason

    jmason Well-Known Member

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    If you save "sight in conditions" in your software it should deal with temp, elevation, and other changes for you and adjust your drops accordingly. That's the design intent behind that feature anyway. The advise AJ gave you will confirm it for you though.
     
  9. elkaholic

    elkaholic Well-Known Member

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    I say amen to AJ's comments....Rich
     
  10. TH

    TH Well-Known Member

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    Thanks guys ill freeze my bullet and run them through the crono at my freezer temp