Appreciate the comments. Based on all comments, what you've outlined is going to me plan moving forward.You got lots of good advice here and I believe your plan to 1) try 60 grs and 2) seating depth tests at 58 grs is a good idea.
I would suggest to 1) double check your action torque and scope mounts, 2) try a few other bullets if the above plans don’t improve accuracy. Not “fancy” high bc bullets but when a rifles picky I ve seen the Sierra GK or ProHunter and the Nosler BT s excel. Personally I d try bullets next before different powders. If a 270 Win doesn’t shoot H4831 typically there’s some other issues!!
Good Luck.