Velocity
The Velocity of the CCI ammunition was probably close to the speed of sound. By shooting in the -1 or -2 Celcius termperature range, it can reduce the cold ammunition in velocity.
It can also depend upon bullet weight. If the CCI stuff was a heavier bullet weight, that would affect velocity.
The only way to find out is to chronograph it. Many, many years ago, I shot Winchester Super-X out of a Remington 581 rifle. At 100 yards, it gave sub-one inch groups. The name Super-X has the connotation of great speed, but it later dawned on me that Super-X was actually target ammunition. Later when chronographs came within reach of the average shooter, I ran some old Super-X through the chronograph, and the speed was just slightly over the speed of sound.
For a practical experiment, you can take a box of ammunition and while at normal temperature, shoot it through the chronograph and get an average. Then stick the other half of the box of ammo into the freezer for a day, and shoot and chronograph it. You will find that the frozen ammo is lower velocity.
One time, living in a city, and faced with a Squirrel problem, I took a box of target .22 ammo and froze it before using it. Problem solved.
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