Do you reload? Could be that you used one of the reloading powders that is sensitive to the weather ...Cold and or heat.
I read in Fish, Fur, and Game that you should bore a hole in the ice and place a woodchuck half in and half out of the hole.. Once it freezes they say just wait them out a the now established food hole. I have seen your pond and often thought now that would be a good place to try this bait station.. However can't remember if there are cabins along the other bank..
I was calling with my son.. In comes an coyotes about 80 yards away.. He places the 22250 with Win 45 grain HP right on it's chest.. I,m watching through my scope and we are both using tripods.. The coyote crumbles and falls to on it's side.. We go to the spot and we couldn't find it.. The more we thought about it must have crawled right down a chuck hole that was right where it fell..This was the Mosquito Creek hunt yet.. Coyotes always have something going for them...