Well the G36 is a plastic gun, ever try shooting a plastic gun when it's -40? Theres a pic somewhere of a G36 that exploded when shot in cold weather lol
Unfortunately warzones don't get closed when the windchill goes past -30
And was it an old M4? or an M4A1? And what kind of ammo did you use? Because it'll jam on anything but high quality ammo unfortunately...