Originally Posted By: HunterLee
BLC2 is not a cold weather powder and found that the hard way. Shot great in the fall working on a load. Come coyote season I was key howling but it was -10.

All my coyote loads are extreme loads. When it gets real cold, like -20, even they seem to lose a little bit.

If you're key holing it's not the powder and most likely not related to the decrease of velocity although that could play a small roll. More than likely it was the drop in temperature as that plays a larger role in stability than 100fps or so in velocity loss.

Most likely your bullet was on the ragged edge of stability and the temperature drop threw it out. The lower the temperature the lower your stability factor will be. Berger has a handy stability calculator that you can play around with by entering your bullet info and twist rate (always best to measure yours since they can easily vary as much as .5"). It's a nice tool to check out.