Originally Posted by
Aragorn243
Don't take this the wrong way as I do not know your shooting style, experience or technique. And my suggestion very well may not be the cause as you say you grouped normally before shooting this particular group.
I am a rifle coach for a high school rifle team. If one of my team members brought me a target that looked like that I would tell him that it is a breathing issue. The shooter is breathing while they shoot.
So before you do anything drastic to the rifle, just make yourself aware of what you are doing before, during, and after you pull the trigger.