y_not5
Here is the deal, if it were me going on a hunt like yours, I am not sure that I would trust the new Rem ML 209 in that cold of weather. To be on the safe side I would go with a hotter primer especially if you are using pellets. I useloose t7 and I know I can get ignition with a 209-4 at sub freezing temps... I am not sure of pellets and at that temperature using a hotter primer will not change you point of impact. As temp goes down so does the effeciancy of your powder... Just some thoughts...
Again Good Luck