Chronograph error or what??

Discussion in 'Long Range Hunting & Shooting' started by Tnwhip, Mar 18, 2013.

  1. Tnwhip

    Tnwhip Well-Known Member

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    Last week I worked up a new load. My chronograph was giving me a reading of 2915 fps Ave. This week the same load was 2886 fps. The second shot on a clean barrel is the only shot out of 11 that went 2921 fps the rest were all 2800s. Sunny skys and only 5 degree difference in the temp from last week. I was using a Win.Large Rifle primer, I decided to try a CCI 250 mag primer. Cut the load back a .5g and it went 2827 ave. Upped the charge back up .5g. It went 2826 ave fps. It did get cloudy, could that be the reason it got slower. This is not the first time this has happened. I have never been able to get the same velocity from day to day. I have had a difference of 200 fps before. I didn't have time to go back and use a WLRP to see what the reading would be. It was also the same brass that I shot last week. It was still shooting good all shots were under MOA out to 500 yds. Impack did not change much with the mag primers. Maybe 1/2" higher at 200 yards. That does not make sence either being slower???
     
  2. Canadian Bushman

    Canadian Bushman Well-Known Member

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    What kind of chrony?
     

  3. Tnwhip

    Tnwhip Well-Known Member

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    ProChrono I have had it for about 20 years. LOL:)
     
  4. 4bycamper

    4bycamper Well-Known Member

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    Do you think the WLR primer is that much hotter?

    I have been aware for some time that the WLR was a hot primer
    but never thought that it was hotter than a CCI 250 mag! :D
     
  5. rick523

    rick523 Well-Known Member

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    Do you set your crony up the exact same way every time? Distance from barrel, perfectly level, same height. Don't just eyeball it, it all makes a difference. IMO
     
  6. Tnwhip

    Tnwhip Well-Known Member

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    I have a chart showing the hotest to the coolest
    Fed 215
    WLRM
    CCI 250
    rem 9 1/2 M
    WLR
    Fed 210
    CCI BR2
    CCI 200
    Rem 9 1/2
     
  7. Tnwhip

    Tnwhip Well-Known Member

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    Yep same spot everytime. I don't measure the distance or height it is very close. I try and make the bullet go 6 or 8 inches over the screens.