I can only state what has been my experience. I do most of my hand load work up in Tucson's hot summers. I figure pressure problems should show up a bit quicker in the heat. My hunts the last seven or so years have been for elk in the Raton New Mexico area, the Vermejo Park ranch to be exact for cow elk. I usually hit the Whiiting range to check my sights the day before the hunt. Rifles tested have been .270 Win., .280 Rem., 30-06, .300 Win. Mag. and .35 Whelen.
The .270, .280 Rem., and .300 Win. Mag. were charged with Winchester Magnum Rifle Powder (WMR). The 30-06 with W70 and the .35 Whelen with Re15.
Loads were worked up at temps ranging from 95* to 115* Won't forget that day.) Temps at the Whittington range ran from 28* to 68 above. Points of impact for all loads were unchanged, even at +6*. Both W760 and WMR were reputed to be very temp sensitive. Brass in all loads was Winchester except for the Whelen which used Remington brass. Primers were standard Winchester WLR. No magnum primers used. Dunno if this proves anythong or nothing, just what I experienced with the above mentioned powders. YMMV.
Paul B.
