same problem with remington 180's out of my marlin xl-7 30.06... 4 inch groups... neck size, and reload good winchester brass with 165gr sierra bthp... 4 shots, .690 group as best group with most being under an inch..
duplicate results with my marlin xl7 25.06 and prvi partisan 90gr hp factory loads... 3 inch groups at best with flyers... neck size and reload the same prvi partisan brass, 75gr sierra varminter hp over 59gr of h4831sc... cover 5 with a quarter, can almost block some of the groups out with a dime
if you are looking for accuracy, i am convinced that reloading is the way to go... i weigh every charge, and neck size only...