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Temperatures effect on velocity for 12 ga.

Discussion in 'Uncategorized Threads' started by BOBL, Aug 5, 2007.

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  1. BOBL

    BOBL TS Member

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    We were having trouble with our chronograph, we thought. I experimented
    with my hand loads at different temps. The temperature was 104 degrees
    and the shells had been setting in my truck for some time. These shells
    averaged 1228 FPS. I placed three shells in the clubhouse freezer for
    five minutes,and a few minutes later they averaged 1139 FPS. My last test
    was to take one shell out of the top of a closed box that had been setting
    in direct sunshine on the back seat of my truck,it tested at 1360 FPS.
    The muzzle was measured five feet from the chrono and other people
    tested there loads and were satisfied with their results.
    My conclusion is that my load will vary winter to summer from 1139 FPS
    to 1228 FPS. AA cases, Clays powder, Fio 616 primers, Claybuster wads.

    Bob
     
  2. g7777777

    g7777777 TS Supporters TS Supporters

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    its probably a combination of primer, compression of the components- and the powder type/batch

    several variables -- powder might the greatest of those-- but from freezer to sun might not be the best comparison either

    could they have been a little more velocity in those shells to begin with?

    Gene
     
  3. bill1269

    bill1269 TS Member

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    I had problem's in the winter with the FIO 616 primers. Started shooting at about 25 degree's shells sounded weak,the coolder it got the weaker they got until by the end of the night most of them would not even go off and that was at 6 degree's.changed primer in the same load and all was good.
     
  4. Quack Shot

    Quack Shot Active Member

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    It's best to test your loads at the temperatures you will be using them at. Just bear in mind that as the temperatures go up, pressures usually follow suit. Selecting a load at or near maximum pressures at the standard temps when the data was compiled could give much higher pressures at normal "summer" temps. I usually select, test, and adjust my loads accordingly.

    Some primer/powder combinations do not work well at low temperatures. I have also had some troubles with The Fiocchi Primers in cold weather, using certain powders. They work just fine over 60 degrees and I will use them when it's warm or select a powder that is less troublesome.
     
  5. Cold Iron

    Cold Iron Active Member

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    The problem is the F616 primers. Trust me. Want to really see a variance try it with Promo powder, of course it depends which batch\blend of Promo you get.....


    The graph shows a 7/8 oz. load with a F616 with Promo and a .040 crimp after coming out of the freezer. Taking the crimp down to .080 helps eliminate the first pressure spike so full combustion can take place. I decided to just go back to Clays and W209.


    The pressure trace was done by someone else who has a lab and was persistent enough to find the problem.
     
  6. mallardfilmore

    mallardfilmore TS Member

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    If you really want to know the effects of temperatures on powder, why don't you call the manufacturers like Hodgon and ask them? They only have a full time ballistician that does this sort of thing for a living.
     
  7. phirel

    phirel TS Member

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    Powder burn rates are affected by temperature. Some types of powder are more sensitive to temperature than others. The Alliant Plant tests powders at -20, 70 and 120 degrees F.

    Pat Ireland
     
  8. zzt

    zzt Well-Known Member

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    Pat, since you have an "in" at Alliant, perhaps you can find out and report on the results of that testing for the old standbys Red & Green Dot and the newbies e3 and American Select.
     
  9. Cold Iron

    Cold Iron Active Member

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    BTW I called both powder manufactures last winter about this. Alliant said they can not reproduce it, although hundreds of us can, not much help there. At least Hodgdon suggested I might try a different primer than the F616 and they seemed aware of the issue. Even though the technical support person had the personality of a bent shit can at Hodgdon I’d rather talk to someone that has a clue.
     
  10. FarmerD

    FarmerD TS Member

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    It's a fact the Fiocchi 616 is a great primer in temperatures above 40 degrees. Unfortunately that don't ignite REX 2, Promo, Green dot in colder temperatures, through my experience with a chronograph. Use FED 209A or RIO in cold temperatures. Richard
     
  11. mecman

    mecman TS Member

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    As Cold iron said Clays w/ w209 primers you can't go wrong at any temp.
     
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