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 US Navy & Palma Rifle Team Member
NRA High Power Master & Long Range High Master
NRA Smallbore Prone Master
Last edited by Bart B.; February 6, 2013 at 04:44 PM.