All smokless powder's temperature sensitive. How much depends on its chemical makeup. I don't know of any table that lists how much each one has, but with everything else on the internet, surely there is one; isn't there?
There's another hot spot in the equasion, too. As a round sits in the chamber of a hot barrel, its powder heats up and makes bullet shoot out faster. Shooting 30 caliber magnums in 1000 yard team matches, I've always come down 1/4 MOA on the sights for every 20 seconds the round's in the chamber if the coach has me wait for the wind to stabilize. Sometime's I've waited 2 minutes or more, then having come down 1.5 MOA on the sights, fired a shot, it struck center, then come back up 1.5 minutes some 20 seconds or so later and fire another shot; it strikes center, too. But it took me some tests to find out how much elevation change to make for each 20 seconds of wait time. Which is why I don't like to keep a round in a hot chamber more than 15 seconds before firing it. It matters at long range. With the .308 Win. I'd come down a quarter every 30 seconds of wait time
US Navy Distinguished Marksman Badge 153
Former USA Palma Team Member
NRA High Power Long Range High Master
NRA Smallbore Prone Master
Last edited by Bart B.; February 6, 2013 at 04:44 PM.