A two-piece locking nut assembly for securing a mantle to a head assembly of a cone crusher. The two-piece locking nut assembly includes an inner nut and an outer nut. The inner nut includes a set of axial bores that each receive a jackscrew. Once the locking nut assembly is in position on the head assembly, the series of jackscrews are tightened to exert a force on the mantle that is counteracted by forces through the inner nut and into the head to create a locking force between the locking nut assembly and the head assembly. The outer nut is turned along the inner nut to hold the locking nut assembly in place. Once the outer nut is moved into position, the jackscrews are removed such that the outer nut continues to apply the locking force between the mantle and the head through the locking nut assembly.