I have had great success with LiPo batteries for guns. Also, the key to keeping warm in winter is light, thin layers, and lots of them! Air is one of the best insulators, and having the gaps between layers of cloth will keep the heat in without restricting too much motion.
The worst thing I have had difficulties with is fingers getting numb. I have a pair of gloves from Mark's Work Warehouse, and they're alright, but not so grand.
I would love to have a skin-tight pair of gloves to go underneath my winter-operator gloves.
Guardians of Asgaard