OP,
I couldn't help but chime in on this and what I'm going to say is likely covered in some of the post above but hopefully from a slightly different approach. The thing that jumped out at me is "ballistics calculator".
When you go to the range the ideal situation is to go with only one purpose and goal in mind. Whether its to shoot groups, chronograph loads, obtain your dope, whatever you do go with the intent of doing that and that only. Know what you expect to do and how you will do it. If you must do more than one thing do them as separate processes and goals. For instance if you know you are shooting at range, run your calculator before hand and carry a range sheet with you. Going from shooter to data input technician and back are two totally different jobs and require totally different trains of thought as you have noticed. While your ballistic data may well be off, you can shoot and adjust (record) based on impact without breaking your position or train of thought. Save the truing to something done away from the range.
Similarly, if you are going to chronograph and shoot for groups, don't do both at the same time (unless you are using a Labradar or magneto speed). You don't want your mind switching from chronograph to group to chronograph.
There are also some things you can do to make your process more consistent. If you are shooting at long range, don't take that first shot at 800 or 1000 yds. Shoot at a comfortable range which is whatever you feel comfortable with, maybe even after some dry firing. You can think of something like this as proving out the system (rifle, ammunition, and shooter). Doing so will aid your confidence in both the rifle and yourself prior to going to the next step.