Pin tumbler assembly

Claim 1

IN A PIN TUMBLER MECHANISM, A CASING HAVING A MAIN BORE, A PLUG ROTATABLY MOUNTED IN SAID BORE, A RADIALLY EXTENDING CROSS BORE IN SAID CASING COMMUNICATING WITH SAID MAIN BORE, A RADIAL PASSAGE FORMED IN SAID PLUG ROTATABLE INTO ALIGNMENT WITH SAID CROSS BORE, A KEYWAY IN SAID PLUG INTERSECTING SAID PASSAGE, A FRANGIBLE FOLLOWER PIN RECIPROCABLE IN SAID PASSAGE, SAID PIN INCLUDING INNER AND OUTER SECTIONS SEPARATED BY A WEAKENED NECK PORTION, A DRIVER PIN RECIPROCABLE IN SAID CROSS BORE, SPRING MEANS IN SAID CASING URGING SAID DRIVER PIN AGAINST SAID OUTER SECTION OF SAID FOLLOWER PIN NORMALLY TO PROJECT SAID DRIVER PIN PARTLY INTO SAID PASSAGE SAID OUTER SECTION INCLUDING MEANS THEREON LIMITING MOVEMENT OF SAID OUTER SECTION INTO SAID PASSAGE, AN OPENING IN SAID CASING COMMUNICATING WITH SAID MAIN BORE AT A POINT BENEATH THE AXIS OF SAID MAIN BORE POSITIONED TO REGISTER WITH SAID PASSAGE IN AT LEAST ONE ROTATED POSITION OF SAID PLUG, SAID OPENING BEING OF A SIZE TO RECEIVE SAID INNER SECTION OF SAID FOLLOWER PIN.