So, I took my 338 out for a stretch today. I developed the load in roughly 70 degrees. I've shot it up to 95 degrees without issues. When I got to the range it was 26 degrees. I got set up and hung targets first. I got the ammo box out of the truck last. First shot at 100...bullseye. Second shot at 200... bullseye. I couldn't see 300 yet due to fog so I waited. It took about an hour for the fog to lift enough to shoot. At 300 yds. I could only get shotgun groups (4" or so) so I waited. Then, At 32 degrees, I tried again. I got back-to -back five shot groups that averaged. 2.54". I waited till the temp rose another two degrees, which took about 40 minutes, and fired two more five shot groups that averaged 1.68" which is normal for this gun and load. I'm thinking I got the first two rounds off before the cases were affected. Then, with an hour wait, they got too cold. So I'm thinking my powder is stable down to 34 degrees. Is it sensible to believe the powder is insensitive to such a big temp swing? 34 - 95 plus degrees?
