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Rifles, Reloading, Optics, Equipment
Reloading
Temp sensitivity of powders
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<blockquote data-quote="papa45" data-source="post: 228811" data-attributes="member: 3916"><p>I concur with what AJ and eddybo said. Basically, warmer temperatures will create higher pressures and higher velocities. Changes in velocity can cause changes in barrel harmonics, which can cause changes in POI. If you are still within the "node" or "sweet spot" for your particular rifle and load, you may not see any difference. If not, you could see large variations in POI or group size. </p><p></p><p>Recently, I tried to gather some data myself on temperature sensitivity. I developed loads for two different rifles that gave me a satisfactory node, using the OCW process. One was a .270, using IMR 4350, and the other was a .300 WM, using RL22. (not apples to apples, but I wanted to see the effect of temperature on my loads.) I measured velocities at ambient air temperatures from 40 to 80 degrees farenheit. The .270 with IMR 4350 increased approx 50 FPS from 40 to 80 degrees. The .300 with RL22 increased approx 70 FPS from 40 to 80 degrees. My POI's moved around a bit, even though I thought I had found a good node. At long range, there could be a significant difference. Bottom line, as already mentioned: test your loads and sight in under the conditions you expect to be hunting.</p></blockquote><p></p>
[QUOTE="papa45, post: 228811, member: 3916"] I concur with what AJ and eddybo said. Basically, warmer temperatures will create higher pressures and higher velocities. Changes in velocity can cause changes in barrel harmonics, which can cause changes in POI. If you are still within the "node" or "sweet spot" for your particular rifle and load, you may not see any difference. If not, you could see large variations in POI or group size. Recently, I tried to gather some data myself on temperature sensitivity. I developed loads for two different rifles that gave me a satisfactory node, using the OCW process. One was a .270, using IMR 4350, and the other was a .300 WM, using RL22. (not apples to apples, but I wanted to see the effect of temperature on my loads.) I measured velocities at ambient air temperatures from 40 to 80 degrees farenheit. The .270 with IMR 4350 increased approx 50 FPS from 40 to 80 degrees. The .300 with RL22 increased approx 70 FPS from 40 to 80 degrees. My POI's moved around a bit, even though I thought I had found a good node. At long range, there could be a significant difference. Bottom line, as already mentioned: test your loads and sight in under the conditions you expect to be hunting. [/QUOTE]
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Rifles, Reloading, Optics, Equipment
Reloading
Temp sensitivity of powders
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