After the original patents had expired ,some of which in the British trade would not stood up to a test case in a court of law, there was free for all so there would have been a whole raft of copies and variations on the original theme . Some were improvements such as the Scott square bolt others a waste of time that had little or no effect on the actual locking other than to look good in adverts .The same will apply to the subsequent variations on the Kersten bolt . The version that the likes of Beretta use will not have specific name other than " top bolt "or "locking bolt"
