The invention relates to a device for adjusting the orientation of a rear stock of a portable firearm relative to a barrel of the portable firearm, comprising a ball joint, which is arranged between the rear stock and a front part fixedly connected to the barrel and which has a first joint part connected in a positionally fixed manner to the front part or the rear stock and a second joint part, which can be pivoted relative to the first joint part and which is connected in a positionally fixed manner to the other of the rear stock or the front part, wherein the first joint part and the second joint part are connected to each other in a pivotable and fixable manner by means of a releasable and fixable fixing apparatus, the fixing apparatus has at least one fixing element, the first joint part has a spherical, in particular ball-shaped, joint head, which is mounted in a corresponding recess of the second joint part, the fixing apparatus has a clamping part, which likewise has a recess for at least partly receiving the spherical joint head, and, in the fixed state, the joint head is clamped between the second joint part and the clamping part by means of the at least one fixing element.