Shooting is both mental and physical. Control the variables (physical), snap in a couple of times, make your best wind call using ALL available information, and get one in the air. Take notes, critique yourself, and challenge yourself to continue to learn. Make it hard, You’ll never get better shooting easy stuff. For your CB shot, really focus on all the fundamentals from sight alignment to follow through. Then, after the CB shot, use the information gained (impact, splash off target, etc...) to further your knowledge.
The mental side is to be confident, but in the event of a miss, to use the failure as information to put into your notes (toolbox) to learn from and carry on to the objective. You can’t unring the bell, or get the shot back that missed. Consider a miss as more information, determine the “why”, and move on.
You didn’t mention at what range you’re seeing this, but with a 300, it is probably something simple in your fundamentals AND your mindset going into the CB shot. Relax, apply the basic fundamentals, and correct, and have fun.