cold bore shot through chrony 40fps higher than next four shots

Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by mikebob, Nov 23, 2010.

  1. mikebob

    mikebob Well-Known Member

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    I bought a new Savage Mod 10 FCP HS Precision in 308. The first cold bore shot is between 2885 and 2875 and the next four shots split hairs with 2846. This is the only factory rifle I own, none of my customs cold bore shot is any differ through the chrony. I did break the bl in and have about 50 more rounds down the tube. It doesn't make any differ clean or little dirty always around 40fps higher. I guess my question is should i make a drop chart with cold bore bullet speed or just average of the five shots like the others.
     
  2. Mikecr

    Mikecr Well-Known Member

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    Two things described here aren't normal..
    1. Velocity is normally LOWER from a cold bore.
    2. Barrels are barrels and all usually do this. It's not like an aftermarket barrelmaker has designed away the cause of lower MV first shots.

    How you would get higher MV 1st shots is a mystery to me.
    But if you're a hunter, the first shot is what matters. The fifth shot doesn't matter at all.
     

  3. D.ID

    D.ID Well-Known Member

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    I am no expert but I found most of my work up loads are faster from a cold bore but I can find a powder charge around max that tightens up the velocity and that load so far has bean the most accurate anyway, so you may want to change your powder charge slightly and see if the spread changes. Of course it's true when hunting the first one is the only one and anything else is an act of desperation, but you should know how it will act in case you need it. Life happens and it isn't always pretty. Good luck.
     
  4. justgoto

    justgoto Well-Known Member

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    My cold bore shot with my new 30-06 is 20FPS slower than the next shots. I used the first shots speed for my drop chart.
     
  5. mikebob

    mikebob Well-Known Member

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    Im going to start reloading for this one pretty soon. I am shooting fed gold medal match 168 now. The spread after the cold bore shot is within 10 fps for 4 shots which to me is amazing for factory loads. What is funny is this thing shoots one hole groups even with the cold bore shot being 40fps faster. Im going to shoot some 600 yard groups cold and see if it makes a big differ at that range. thanks for the input this one has got me stumped.