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Chronograph error or what??

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  #1  
Unread 03-18-2013, 02:13 PM
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Join Date: Mar 2011
Location: Tennessee
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Chronograph error or what??

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???
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  •   #2  
    Unread 03-18-2013, 03:30 PM
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    Join Date: Jan 2012
    Location: Houston, Texas
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    Re: Chronograph error or what??

    What kind of chrony?
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      #3  
    Unread 03-18-2013, 04:32 PM
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    Join Date: Mar 2011
    Location: Tennessee
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    Re: Chronograph error or what??

    Quote:
    Originally Posted by Canadian Bushman View Post
    What kind of chrony?
    ProChrono I have had it for about 20 years. LOL
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      #4  
    Unread 03-18-2013, 04:38 PM
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    Join Date: Apr 2009
    Location: Eastern Colorado
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    Re: Chronograph error or what??

    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!
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      #5  
    Unread 03-18-2013, 04:51 PM
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    Join Date: Apr 2012
    Location: Terre Haute In.
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    Re: Chronograph error or what??

    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
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    Rick

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      #6  
    Unread 03-18-2013, 05:00 PM
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    Join Date: Mar 2011
    Location: Tennessee
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    Re: Chronograph error or what??

    Quote:
    Originally Posted by 4bycamper View Post
    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!
    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
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      #7  
    Unread 03-18-2013, 05:05 PM
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    Join Date: Mar 2011
    Location: Tennessee
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    Re: Chronograph error or what??

    Quote:
    Originally Posted by rick523 View Post
    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
    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.
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