The machine gun has an automatic-only trigger mechanism and a cross-bolt safety in the form of a button that is operated by the shooting hand (in its "safe" position the bolt release is disabled). The weapon fires from an open bolt. The cyclic rate can be altered by installing different bolts and recoil springs. A heavier bolt uses more recoil energy to overcome inertia, thus slowing the action. On MG 3 machine guns, two types of bolts are available, with standard weight (about ) for the standard 1,000–1,200 rounds per minute cyclic rate of fire and with extra weight (about ) for a slower 800–950 rounds per minute cyclic rate of fire. Those bolts also are used along with different return springs.
