Re: Load development in 0 deg temps?
Really depends on what you plan on doing. My rule is to always work up loads during spring and fall when it is near actual hunting temps when I'll use THAT rifle.
However, interestingly enough, I'll be in Ontario in about 7 weeks on my first wolf hunt. I am specifically going to use a medium powder (varget or H4350) in my 270, and a magnum primer. I will be working up these loads between now and then and will choose very cold days here, which, yesterday, it was 3 degrees when I went to work.
I'm told to expect -20 to -40 degrees F when we are out for wolf. So, I want something as HOT as I can get it, safely. I've been advised to steer away from slower powders that would work well in more common temps where I rifle hunt which is above zero all the way up to 70, even 80 degrees. I've heard that some common hunting loads here can be a squib load there, such as my 130 gr solid base over 58.0 Re22 and a 210M primer. Since I have no experience shooting in temps below -10, I have relied on feedback from those who do.
I will be sparing in my numbers and will batch these loads separate from all others and label them "wolf loads/-20 plus." I wouldn't want to go play at the range in 60+ degrees with these hotter loads and have a problem.
The outfitter has stated that he really prefers a 150 gr bullet for wolf but I have such a kickass load in one of my 270s that is already proven, but I'd like to try it with a magnum primer: 130 TTSX over 56.0 H4350. That load shoots just fine at 80 degrees. I'll back off about 4 grains and start with a magnum primer to see how it does, working back up to max.