The coldest I have done any target shooting has been 17 degrees above. I usually can handle mid-20's on a regular basis, use wool socks. The problem is that I sit for 2-3 hours on a wooden seat, if I was hunting, it would not be so bad. This is in the Minneapolis, MN area.
I also use light cotton working gloves to allow me some sensitivity to the trigger without having my hands exposed, even then I have to periodically put them down my shirt to warm up. I have proper heavy gloves, but they lack the contact to the trigger that gets me the good groups.
I like how the rifle barrels cool down fast, not at all like shooting when it is 90 degrees and humid! After my Yugo Mauser was hangfiring I came up with an idea to shoot in cold weather without degreasing the bolt. After firing a few rounds, bring a plastic sandwich bag, put the bolt into it, and then put it down your shirt, under your armpit, etc. for a few minutes. That should keep it warm. Then pop it back into the rifle, shoot 5-10 rounds, then back into the plastic, under the armpit, repeat. I haven't tried this yet, but it should work for everybody in the cold climate.