Can temperature alone get you into danger zone?

Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by Desert Fox, Jun 24, 2007.

  1. Desert Fox

    Desert Fox Well-Known Member

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    When I developed the load for my 308, I settled on 45 grains of BLC-2 to propell the 168 grain Nosler Comp bullet at around 2750 fps. Accuracy was excellent and pressure was normal. I thought, I found a really good load combining accuracy and velocity until one day last summer when I got into trouble shooting this load in a 105 degree ambient temperature. I pretty much beat-open the bolt handle, using the plastic handle of a large screw driver. So my question is...can temperature alone get you into danger zone? or is the case design, brass thickness, chamber tightness has a lot to do with it? What's the velocity increased (fps)expected per degree rise in temperature? Enquiring mind want's to know. RJ
     
  2. Ridge Runner

    Ridge Runner Well-Known Member

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    ball powders are more tempature sensative than extruded powders, and yes, in hot weather they'll go overpressure if they are loaded to max in cooler temps.
    JS
     

  3. LewisH

    LewisH Well-Known Member

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    [ QUOTE ]
    So my question is...can temperature alone get you into danger zone?RJ

    [/ QUOTE ]

    Agree with JS absolutely!

    I just finished pulling the bullets from a whole bunch of 220 Swift Improved loads (H414) which were near max when tested in cool California, and much too hot in the warm Wyoming prairie dog towns...I knew better, too...really dumb. /ubbthreads/images/graemlins/tongue.gif
     
  4. ol mike

    ol mike Well-Known Member

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    I had the same problem weekend before last.
    My 22-250 & 25-06 both had hard bolt thrust and cratered primers.
    The 22 load is 41.3gr of h-380 -55gr sierra blzkg.
    25-06 max load w/h-4831 w/a 85gr n-bt.
    Both guns were off by a good bit on the drop chart.And the 25-06 was grouping 1.5 to 1.7" not its usual .5-.6".
    By the way it was 96* and high noon -the gun barrels were hotter than hell from the sun alone.
    Also the POI was off on both rifles.
    Also shot my cz 221 fb -as usual shot like a champ !Max load- AA 1680 ball powder w/a 40 gr n-bt !!!?
     
  5. eshell

    eshell Well-Known Member

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    Even factory ammo can be sensitive to excessively high temperatures.

    We shoot regularly and have conducted rifle classes at Qauntico Marine Corps Base when ambient temps exceed the mid 90s. It only takes a few minutes in direct sun or a hot barrel to make even factory ammo show pressure signs and hard extraction.
     
  6. RMulhern

    RMulhern Well-Known Member

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    Over temp?

    Ammo you may can load safely for temps in December/January might work just fine; NOT IN JULY/AUGUST!!
     
  7. Freebore

    Freebore Well-Known Member

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    Yes, hot temperature alone can get you in trouble as you found out. I'm sure someone has a thought out chart on temperature rise vs pressure, I do not however.
     
  8. MSU Marksman

    MSU Marksman Well-Known Member

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    Another factor that temp can play, is with the bullet's seating depth. I loaded some compressed loads in early April, and by July, the bullets started creeping outwards.