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Rifles, Reloading, Optics, Equipment
Rifles, Bullets, Barrels & Ballistics
Chronograph issues?
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<blockquote data-quote="davkrat" data-source="post: 1075319" data-attributes="member: 6452"><p>I have a basic Shooting Chrony that has given me some strange readings lately. My load in the 7mm Rem Mag is 69.0 grains of H1000 and the 150 ETips. I regularly get an average velocity of 3131 fps and SD of 15. The last time I went out the exact same load averaged 2907 with an SD of 17 for 10 shots. My barrel does tend to copper foul with the ETips and I regularly give it a thorough cleaning. Anything that could cause an extreme drop of 200+ fps in velocity other than a faulty chronograph? These results were only a few weeks apart in nearly identical conditions, around 70 degrees ambient so no extreme temp changes. The fact it was consistently so inconsistent has me scratching my head. </p><p></p><p>I am shooting a pretty much maximum load out of a 26" barrel so I do not think the higher velocity is outside the realm of possibility of the 7mm Rem Mag and the drops match up very well at that speed.</p></blockquote><p></p>
[QUOTE="davkrat, post: 1075319, member: 6452"] I have a basic Shooting Chrony that has given me some strange readings lately. My load in the 7mm Rem Mag is 69.0 grains of H1000 and the 150 ETips. I regularly get an average velocity of 3131 fps and SD of 15. The last time I went out the exact same load averaged 2907 with an SD of 17 for 10 shots. My barrel does tend to copper foul with the ETips and I regularly give it a thorough cleaning. Anything that could cause an extreme drop of 200+ fps in velocity other than a faulty chronograph? These results were only a few weeks apart in nearly identical conditions, around 70 degrees ambient so no extreme temp changes. The fact it was consistently so inconsistent has me scratching my head. I am shooting a pretty much maximum load out of a 26" barrel so I do not think the higher velocity is outside the realm of possibility of the 7mm Rem Mag and the drops match up very well at that speed. [/QUOTE]
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Chronograph issues?
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