http://www.carl-walther.de/files/pdf/262_81_21_f_P99_ENGLISH.pdf
3.3.4.1 P99 AS, Double Action Trigger
• Load the pistol and de-cock it. Keep the muzzle pointed in a safe direction. Keep
your finger off the trigger and outside the trigger guard until you are ready to fire.
CAUTION: The striker will re-cock if the slide is moved to the rear by about
10 mm. The trigger will remain in its forward-most position
(see Anti-Stress-Trigger below).
• While holding the grip firmly, squeeze the trigger fully to the rear to fire.
• Keep your finger off the trigger and outside the trigger guard until you are ready to
fire again.
The subsequent shots will be fired with traditional Single Action trigger until the
P99 AS pistol is reset to Double Action by pressing the decocker.
3.3.4.2 P99 AS, Single Action Trigger
Traditional Single Action Trigger
After firing the first round all subsequent rounds will be fired with a traditional Single
Action trigger, until the pistol is reset to Double Action by pressing the decocker.
Anti-Stress Trigger
It is called “Anti-Stress” because the trigger pull of the P99 AS is the same length for
the first shot, regardless of whether it is double-action or single-action. The Anti-
Stress trigger functions as a sort of two-stage trigger, and lessens the possibility of a
stress-induced unintentional discharge.
Unlike the operation when shooting - when the trigger does not move all the way
forward between shots - any time the slide is retracted by hand the trigger moves to
its forward-most position. The combination of the trigger in the forward-most position
with the striker cocked is the main feature of the Anti-Stress trigger.
a) Shifting to Anti-Stress trigger mode by manually reloading
The Anti-Stress mode is activated each time the pistol is reloaded manually while the
finger is off the trigger.b)
Shifting to Anti-Stress trigger mode by manually cocking
The Anti-Stress mode is also activated each time the pistol is cocked manually while
the finger is off the trigger:
Hold the de-cocked pistol with your finger off the trigger and outside the trigger
guard, point the muzzle in a safe direction. Pull back the slide by about 10 mm and
then move it back to its forward position. This puts the pistol in Anti-Stress mode(
trigger in the forward-most position and the striker cocked).If the slide gets pulled to the rear more than 20 mm, a cartridge in the chamber
is ejected.
To fire a shot after such manual cocking, squeeze the trigger. When the trigger is
released, subsequent rounds will be fired using the traditional Single Action trigger
with a shorter trigger pull, until the P99 AS pistol gets reset to Double Action by
pressing the decocker.