Abstract: A bayonet-connector-like breech lock has a breech housing and a breech block with at least two radially projecting locking components. The enlarged region needed to rotate the locking components takes the form of an annular space wherein a locking sleeve is fitted to rotate between an open and a locked end position. The locking sleeve has a widened section for each locking component aligned with a widened part of the breech block bore in the open end position. The annular space is completely filled by the locking sleeve and the pushed-in breech block.