The invention relates to a rotary lug breech comprising: a breech carrier (1); a breach head (100) mounted therein and comprising a plurality of breech lugs (104); and a locking piece (200) comprising a plurality of locking lugs (204). A rearward facing cam section (208) is formed in the locking piece (200) on a locking lug (204). When the breech head (100) is released, said cam section converts a release motion, during which rear end faces (106) of the breech lugs (104) detach from front end faces (206) of the locking lugs (204), by means of a forward facing control section (132) correspondingly formed on a control breech lug (104h') into a screwing motion of the breech head (100) in order to release a cartridge case retained in the breech head (100) from a cartridge chamber, during which screwing motion the control section (132) is supported on the cam section (208). During locking, the cam section performs a pre-control function, which rotates a control pin (102) in a control gate (60) of the breech carrier (1) from an axial stop (70) into a control position in which the control gate (60) engages at a locking edge (62) with the control pin (102) and, when the breech carrier (1) moves forward relative to the breech head (100), exerts a rotary momentum on the breech head (100) and thus converts a linear feed motion of the breech head into a locking motion by means of screwing motion.