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???
Chronograph error or what??
- Thread starter Tnwhip
- Start date
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Canadian Bushman
Well-Known Member
What kind of chrony?
ProChrono I have had it for about 20 years. LOL
4bycamper
Well-Known Member
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 been aware for some time that the WLR was a hot primer
but never thought that it was hotter than a CCI 250 mag!
rick523
Well-Known Member
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
I have a chart showing the hotest to the coolestDo 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!
Fed 215
WLRM
CCI 250
rem 9 1/2 M
WLR
Fed 210
CCI BR2
CCI 200
Rem 9 1/2
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.
