Abstract: The present invention relates to a locking lug insert which is inserted into the locking lug recess of a bolt action receiver. The insert defines a central aperture aligned with an elongated chamber in the receiver and one or more cut-out portions opening into the central aperture, one cut-out aligned with each locking lug groove. The cut-out portions are equal in number to the number of locking lug grooves formed in the receiver. The cut-out portions are sized so as to accommodate the locking lugs of the bolt when the bolt is in its closed position. The insert is caused to rotate in the locking lug recess when the bolt rotates, due to the interengagement of the locking lugs, with the cut-out portions.