I plinked last winter with 5-6 different kinds of ammo in my Marlin. I wanted to see which brand shot the best. Range was short, 30-ish yards and I was shooting 7 shot groups. It was probably -20 or -25C out at our winter camp.
After my first 2-3 groups, I was ready to throw the gun away. I had grapefruit to cantaloupe sized groups. Figured I would keep going, since it might just be the ammo. After 7-8 groups (I went back and re-shot some brands), with the best performing ammo, I had 5 of the 7 shots in a ragged hole. I was amazed at how the groups shrank and shrank as I kept shooting. Really opened my eyes to cold weather performance, especially when you only get one shot hunting small game in the winter.
That doesn't really answer your question. I saw no repeatable difference in how the point of impact shifted compared to warm weather. But I use the same gun to hunt in the fall (0 to -15C) and never change the scope settings. It still knocks down birds and hares.
