The P99AS has three different trigger pulls in all (Anti Stress, single action, double action). The QA only has one (heavy 8.4lb single action trigger).
When you rack the slide on a P99AS, the trigger is fully forward but more than 50% of the pull is now 100% no weight. It hits a middle point and locks the trigger at mid point. The final pull is a 4lb single action. This fully forward with 100% reduced weight for more than 50% of the pull is the AS (Anti Stress) trigger. (P99AS Trigger 1)
Once you fire, you are now in single action only at that point. Very VERY short pull/reset at 4lbs. This is the PPQ trigger at this point. The P99AS is actually lighter of a pull than the PPQ. However, this single action is the PPQ single action trigger. (P99AS Trigger 2)
If you ever hit the decocker, the trigger is full forward and full weight throughout. You never have full weight double action pull unless you hit the decocker. (P99AS Trigger 3).
Your QA is like a PPQ or P99SA in single action, however the weight is double. The decocker deactivates the trigger completely. It's used for cleaning. This is the version the Canik TP9SA copies.
The P99 DOA is full weight throughout the pull.