[jmr40]

All of the testing and data I've seen on cold temps is with center fire rifle ammo. With that in mind around 2 fps loss for each one degree is about right with MOST powder. Some powder however is much less sensitive and will only see around 1/2 fps loss per 1 degree. But I've not seen any testing with 22 rimfires in cold temps. I just don't know how much cold effects that ammo.

Also, normally you get muzzle flip in a handgun and the bullet that stays in the barrel longer will impact higher because the muzzle is higher when the bullet exits. But does a 22 recoil enough to have the same effect?

Another theory. Just a guess really. But most 22 ammo has grease in the grooves of the bullet. In extreme cold that grease is going to be a lot harder, and it could have an effect on bullet impact.

It seems to me that the cold temps are causing this. Exactly how may still be a mystery. Wait until temps warm up and get back to the range with the same ammo and report back.