Have any of you who hunt with swfa scopes had your turrets shift? I had this problem with a vortex scope riding behind me in a sled on a snow machine. The windage turret was spun almost one full revolution. Missed a caribou at 300 yards when the day before I had taken one at 475. Anyway, I would consider a swfa 3-9 with uncapped turrets if they are not prone to shift. Thanks