I don't know about cold weather causing erratic groups but it damn sure can cause any old oil, filth or gunk in the firing pin mechanism and even the bolt to gum up and cause misfires or hang fires. My bet is there is nothing wrong with that ammo.
When it gets that cold oil is your enemy, graphite is your friend.
"You cannot invade mainland America. There would be a rifle behind every blade of grass"
~Admiral Yamamoto~
When the people fear their government, there is tyranny; when the government fears the people, there is liberty. ~Thomas Jefferson~
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