P99 was very unique for a striker fired gun, true da/sa with a de-cocker. It has a very nice trigger as well, think da/sa version of the PPQ. It was my first pistol, guess I have a soft spot.
The P99 was introduced in the 90's ans the PPQ sometime in the 2000's.
It has 3 triggers in one. The following is from the Walther forum written by imaoldfat.
Walther P99 Trigger Systems
AS: Anti-Stress
Affected Models: Classic P99 / P99 AS / P99c AS
Trigger Travel: 0.55? Double Action & AS / 0.31? Single Action
Trigger Reset: 0.25?
Trigger Weight: 11 lbs. Double Action / 5 lbs. Single Action
The P99 AS is basically a hammerless Traditional Double Action pistol, which happens to be striker fired. The largest confusion in the trigger system is the AS mode itself, and with out that variable, the pistol would have a similar trigger action to a Sig Sauer or a Heckler and Koch.
The AS trigger system of the Walther P99 has three possible carry modes:
AS Mode
The AS mode is automatically engage after a round is chambered. The trigger is fully forward, as if in double action, but the striker indicator is to the rear and visible. This mode offers the safety of carrying the P99 AS in single action with a light yet long trigger pull.
DA Mode
The Double Action mode is achieved after a round is chambered and the decocking button is depressed, releasing the striker into a double action trigger pull. In this mode the trigger is fully forward and the striker is at rest and no longer visible to the rear of the slide. After the trigger is first pulled, all subsequent shots will be in single action. This mode is considered, among fellow P99 AS owners, to be the safest mode to carry the AS in.
SA Mode
The SA mode of carry for the P99 AS is Single Action. This mode can be achieved by chambering a round, which also places the trigger all the way forward and into the AS mode, then slowly pulling the trigger to the rear until you hear the SA portion of the sear engage. You?ll hear a ?click? and the trigger will remain in this rearward (actually middle/center) position. This mode will also automatically engage after the first trigger pull in double action mode.