SIG SAUER SWISS ARMS SG552 - Manual (Page 28)

This trigger function is only interrupted when the trigger
(8) is released. In doing so the link between the automatic
fire pawl (11) and the trigger rod (4) is disconnected.
The trigger rod (4) moves downward and catches
the hammer (3).
55
Function
5.2.5. Full auto fire
The safety lever (6) is set on "20”. The automatic fire
pawl (11) which supports the trigger rod (4) lies in the
groove of the safety shaft (7). By pulling the trigger (8)
the trigger rod (4) is drawn to the rear and supported
by the automatic fire pawl (11). The hammer (3) is released and strikes forward
(refer to illu. 66).
The recoiling bolt cocks the hammer (3) which is retained
by the sear (5) (refer to illu. 67).
The advancing bolt presses on the release bar (2) which
pushes the sear (5) to the rear thus releasing the hammer
(3) (refer to illu. 71).
Function
54
illu. 73) Trigger mechanism during full auto fire illu. 74) Interruption of fully automatic fire