A test:
http://www.shootingsoftware.com/ftp/Pressure Factors.pdf
From it:
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Both barrel temperature and powder temperature are
important variables, and they are not the same variable. If you fail to take barrel
temperature into account while doing pressure testing, your test results will be very
significantly affected.
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If you're not controlling barrel temperature, you about as well might not bother
controlling powder temperature, either. In the cases investigated, barrel temperature is a
much stronger variable than powder temperature.
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The pressures generated by IMR4350 and H4350 are, for all practical purposes, equally affected
by powder temperature in this case. Yet Hodgdon advertises that their "Extreme Powders" are not
affected by temperature.
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