Can't close bolt on rifle

First make sure the the sizing die is adjusted so that the shell holder contacts the base of the die when the ram is at the top  of its stroke when resizing a case.  This ensures that the sizing die is bumping the shoulder back as well as reducing the diameter of the case.  If the shell holder does not contact the base of the die, the diameter of the case is squeezed down, making the case (and distance to the shoulder) longer.

If this does not solve the problem, return the sizing die with a couple of fired cases, and we can modify the die to suit.  Our address is: 

Lee Precision Inc,
4275 Hwy. U
Hartford, WI  53027.