I own a Smith & Wesson SW99 which is identical in operation to the Walther. It's still one of my favorite handguns. The trigger and it's operating "modes" are unique, but make for a sweet shooting gun. I would recommend that you spend considerable range time with it to familiarize yourself with it's operation, especially the mag release. I used to shoot mine at IDPA matches. Once you chamber a round, the trigger is set in "SA" mode. If you are holstering the gun, I would recommend manually placing the gun in "DA" mode with the de-cocker. If you are going from chambering to firing, then leave it in "SA" mode and fire away. BTW, you might want to check out the PPQ. If you like the P99, you will love the PPQ. It has all the same cool features, but feels even better in the hand.