Pete,
Just bought my Labradar this spring so haven't used it in real cold, but the directions say it shouldn't be used in real cold, as I recall not below about +20 Fahrenheit.
However, it would NOT have to be outside a shooting house, because in fact it needs to be at least a little bit BEHIND the muzzle, and farther back when shooting rifles with muzzle brakes. In the photo, the muzzle of the 7mm magnum I'm shooting is 1-2" in front.
It also supposedly doesn't work with bullets below .20 caliber or velocities much above 3900 fps. Some users have reported occasional exceptions, but so far mine has not worked when I tried it with .17 caliber bullets or .20's at 4400.
