Hold on here - What was the temp? You said you aimed at a deer and click! Then you left the load in the rifle overnight and it fired perfectly the next morning? Was the rifle indoors overnight?
If so, I have a feeling it isn't the primers but the firing pin not hitting hard enough. Especially if it was cold. I'd take that bolt out and spray the crap out of it inside with carb cleaner or some other degreaser and apply a very light coat of WD-40 .
Sounds to me as though you have a gunk build up in the bolt assembly.