More and more we see a clean barrel bench rest “cold shot” shoot higher an inch or two and then as the barrel warms the shots group lower and tight. So some shooters call the first shot a flyer and are happy with the other group and adjust the scope for the group. Not so fast, if you are hunting, it was that first shot that counted. Two things are happening here. First is a clean barrel perhaps with some lubricant or cleaning agent adhering to the barrel affecting the cold shot. Second is the cold barrel shot itself. Veteran hunters advise taking a fouling shot or two and then with a cold barrel shoot for group marking the first shot as the one that counted and adjust the scope accordingly. That works with recent fouling shots and is my method. However, a recent article below experimented with fouling shots to find that they work. But the experiment also included a clean barrel that was finished with a barrel degreaser to remove any lube or residue and fired a cold barrel shot.  Check it out. We may learn something here.

https://www.outdoorlife.com/how-to-shoot-straight-with-cold-barrel/

Good Shooting!