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Rifles, Reloading, Optics, Equipment
Reloading
Cold temp caused faster speeds
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<blockquote data-quote="cohunt" data-source="post: 2064980" data-attributes="member: 94491"><p>I'm not a metallurgist, but this has been covered before by some "in the know".</p><p>Iirc they came to the conclusion that a cold bore to cold bullet will not create extra pressure as they did calculations that both lead and copper (bullet) will shrink more than the steel bore diameter will so theoretically you should have larger clearances/less pressure between bullet and bore when cold-- even so, iirc there are larger tolerances in the actual machining of bores and bullets than the cold Temps would change it anyway.</p><p>It comes down to other variables such as "bullet weld", powder temp instability, primer temp stability, powder lot variances, etc.</p><p>OP said he thinks he figured this out being a seating depth issue anyway.</p><p>Problem is there are so many variables that come into play its hard to prove which one is affecting the velocity, so testing and backing up with multiple testing data sessions is necessary to know what happens to your rifle/ammo combo in cold vs hot temps.</p><p>Some people have seen re26 spike above 85 degrees, others have not-- is that due to lot variances or other variables? Since there is no real practical way for us to chemically test powders we just jave to test and record data for our combo</p></blockquote><p></p>
[QUOTE="cohunt, post: 2064980, member: 94491"] I'm not a metallurgist, but this has been covered before by some "in the know". Iirc they came to the conclusion that a cold bore to cold bullet will not create extra pressure as they did calculations that both lead and copper (bullet) will shrink more than the steel bore diameter will so theoretically you should have larger clearances/less pressure between bullet and bore when cold-- even so, iirc there are larger tolerances in the actual machining of bores and bullets than the cold Temps would change it anyway. It comes down to other variables such as "bullet weld", powder temp instability, primer temp stability, powder lot variances, etc. OP said he thinks he figured this out being a seating depth issue anyway. Problem is there are so many variables that come into play its hard to prove which one is affecting the velocity, so testing and backing up with multiple testing data sessions is necessary to know what happens to your rifle/ammo combo in cold vs hot temps. Some people have seen re26 spike above 85 degrees, others have not-- is that due to lot variances or other variables? Since there is no real practical way for us to chemically test powders we just jave to test and record data for our combo [/QUOTE]
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Rifles, Reloading, Optics, Equipment
Reloading
Cold temp caused faster speeds
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