The Walther PPQ is not a true new design. It shares its engineering principles and main features with the Walther P99QA variant of the P99 pistol that was introduced in 1996. Many modifications compared to the Walther P99QA like the re-designed grip, trigger guard and slide with forward (big) serrations made their combined appearance in 2008 in the Walther P99 RAD, a P99 variant made in Poland and marketed as a military sidearm proposition and the Walther P99Q police pistol. Due to product evolution the PPQ maintains compatibility with both P99 sights and P99 second-generation magazines and other accessories.
The main innovation of the PPQ over the P99QA, P99 RAD and P99Q is its 'Quick Defense' trigger.
The Walther PPQ is a short recoil-operated locked breech semi-automatic pistol that uses a modified Browning cam-lock system adapted from the Hi-Power pistol. The PPQ has a glassfiber-reinforced polymer frame and steel slide assembly. It can be broken down into its main parts or field stripped with a take down catch without the help of tools. The internal preset striker 'Quick Defense' trigger of the PPQ is a departure of previous Walther pistols and has been developed for the PPQ. When the trigger is pulled the trigger bar engages a disconnect lever, which props up a sear hook, which releases the fully pre-loaded striker assembly, firing the pistol. Pulling the trigger does not partially load the striker spring as with the Glock and many other striker fired pistol designs. The PPQ trigger pull is entirely due to the trigger and disconnector springs. The PPQ has a trigger travel of approximately 9 mm (0.4 in) with a relatively short trigger reset of 2.5 mm (0.1 in) and a trigger pull of approximately 25 N (5.6 lbf). Unlike many other trigger systems, preset internal strikers have a let-off point and trigger pull that remains unchanged from the first shot to the last and requires no decocker. It should however be noted that the striker of the PPQ variant does not protrude from the back of the slide, as the firearm is in a constant cocked state. Due to its trigger characteristics the PPQ pistol is marketed by Walther in Germany as a special forces pistol and not as a police duty pistol. According to the Technical Specifications (TR) of the German Police (Technische Richtlinie Pistolen im Kaliber 9mm x 19, Revision January 2008) for obtaining a German Police duty pistol certification a first shot trigger pull of ≥30 N (6.7 lbf), a trigger travel of ≥10 mm (0.4 in) and a trigger reset of ≥4 mm (0.2 in) are required. The PPQ's trigger has been praised as one of the finest factory triggers and perfect for self-defense, but is often thought of as too light for beginning shooters.
Ergonomics and fully ambidextrous controls were a key focus in the design of the firearm, and as a result, three interchangeable grip backstraps are included (small, medium and large) to accommodate various hand shapes and sizes; this feature permits most shooters a comfortable and efficient grip on the firearm. Many have compared the PPQ's ergonomic grip to the HK P30. The injection molded grip frame contains four steel guide rails for the slide: two at the rear of the frame, and the remaining pair above the front of the trigger guard. The trigger guard itself is squared off at the front and textured. The sculpted polymer grip has a texturized 'HI-GRIP' non-slip surface on the sides and both the front and rear backstraps and a slightly funneled magazine well to aid magazine insertion. The hollow cross pin that secures the lower end of the backstrap was designed to function as a loophole for attachment of a lanyard. Under the dust cover the grip frame has an integrated mounting MIL-STD-1913 (Picatinny) rail for attaching accessories, such as a tactical light or laser pointer. The slide and other metal parts of the pistol are Tenifer treated (a nitriding process also used on Glock pistols). The Tenifer finish is between 0.04 mm (0.002 in) and 0.05 mm (0.002 in) in thickness, and is characterized by extreme resistance to wear and corrosion; it penetrates the metal, and treated parts have similar properties even below the surface to a certain depth. The Tenifer process produces a matte gray-colored, non-glare surface with a 64 Rockwell C hardness rating and a 99% resistance to salt water corrosion (which meets or exceeds stainless steel specifications), making the PPQ particularly suitable for individuals carrying the pistol concealed as the highly chloride-resistant finish allows the pistol to better endure the effects of perspiration. PPQ pistols are delivered in a polymer pistol case containing; the pistol, three backstraps of different sizes, two magazines, magazine loader, instruction manual, warranty papers, factory test target showing five shots fired at 15 m (16 yd) distance and an envelope with the case of the proof round fired during the proof test at the C.I.P. accredited Beschussamt Ulm (Proof House Ulm).
The PPQ pistol's barrel is rifled with traditional lands and grooves to stabilize the bullet in flight. The PPQ features three internal safeties (trigger safety, firing pin safety and disconnector safety) of which the external integrated trigger safety inner lever mechanism contained within the trigger serves as an additional passive drop safety. The pistol has a loaded chamber indicator in the form of an extractor on the right side of the slide that gets recessed in the slide when a cartridge is present in the chamber. When the extractor is recessed a red coloured indicator at the end of the extractor also becomes visible. The PPQ feeds from staggered-column or double stack magazines of varying capacity. Walther also offers staggered-column magazines with a +2 baseplate that add 2 rounds to the magazine capacity at the expense of extending the grip and the pistol height by approximately 18 mm (0.7 in). For jurisdictions which restrict magazine capacity to 10 rounds, Walther offers single stack 10-round magazines. The magazines are made of steel for Walther by the Italian subcontractor Mec-Gar and have an anti friction coating for easy loading and anti-corrosion and witness holes to view how many rounds are in the magazine. A steel spring drives an orange coloured plastic follower. The standard staggered-column PPQ magazines weigh 80 g (2.8 oz) After the last cartridge has been fired, the magazine follower exerts upward pressure on the slide stop causing it to engage the slide stop notch thereby holding it in the "open" position. The slide stop release levers are located on the left and right sides of the frame directly beneath the slide and can be manipulated by the thumb of the shooting hand. When a cartridge is present in the chamber the pistol can be fired without the need of having a magazine inserted in the weapon.
Empty magazines are released by depressing ambidextrous magazine release levers incorporated into the trigger guard in all non M2 PPQ variants or by depressing a reversible thumb release push-button located behind the bottom of the trigger guard in the PPQ M2 variant. Additionally, the PPQ M2 magazines are not compatible with the original PPQ magazines. The standard iron sights are made of steel or polymer depending on the country in which the pistol is sold. The rear sighting element is adjustable for windage by a screw and the front sighting element can be adjusted for elevation by exchanging the front sight. For this Walther offers front sight elements in four differing heights and rear sight elements in two differing heights. The standard sights have 3 high-contrast dots which serve as contrast enhancements and have been painted with afterglow paint to aid target acquisition under unfavourable lighting conditions. Tritium illuminated night sights are also available. Due to product evolution in the Walther pistol line the PPQ maintains compatibility with Walther P99 and Walther PPS sights. The sight radius is 156 mm (6.1 in) for the PPQ 9×19mm Parabellum models and 158 mm (6.2 in) for the PPQ .40 S&W models. Factory accessories include: fixed metal 3-dot iron sights, fixed tritium night sights, adjustable sports iron sights, adjustable optic fibre iron sights, laser pointers, tactical lights, magazine flashlight adapters, holsters, magazines, magazine loaders, grip extenders and a suppressor kit with a 118 mm (4.6 in) barrel, protective cap for the muzzle threads and a sound suppressor of the Impuls II-A product line made by Brügger & Thomet are offered as factory accessories. For the recording of weapon specific data, a passive RFID transponder may be integrated into the backstrap of the pistol. The stored data can be read via an external unit.