Should mention those tear open heater packs that are full of harmless iron oxide. They can be quite useful but their main drawback is that they need oxygen to work and there isn't that much available inside winter gloves or boots. That prolongs their working life of course- it's a tradeoff.
Electrically heated gloves- I've never seen a pair that have heating wires in the fingers, just be aware. My best combo in the teeth of an Ottawa winter was insulated gloves inside a thin wind and waterproof goretex shell mitten, purchased separately. Works in extreme cold and in freezing rain storms. For hunting, a really thin pair of contact gloves inside those would have been ideal- but I don't hunt at those temperatures, if only because all the seasons are closed.