[1] Design work on this new generation sidearm began in 1994, and the handgun was presented in 1997 with series production commencing that same year.

[4] The Walther P99Q was also chosen in 2012 to replace older pistols and revolvers of the Finnish Police, Customs and Border Guard.

Walther also took the opportunity to redesign the slide so the user could grip it more easily, and notably, change the proprietary accessory rail to a Weaver type.

All subsequent shots are fired in standard single action mode, where the slack on the trigger is much shorter, but the point of release feels the same.

In order to deactivate Single-Action or Anti-Stress mode, the user can manipulate the decocker button on the top of the slide, just in front of the rear sights.

The striker protrudes visibly and palpably from the back of the slide when the firearm is in a constant partially cocked state.

However, the striker of the second generation P99QA variant does not protrude from the back of the slide, unless fired, as the firearm is in a constant partially cocked state.

The Tenifer finish is between 0.04 and 0.05 mm (0.002 and 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.

[11] 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),[12] making the P99 particularly suitable for individuals carrying the pistol concealed as the highly chloride-resistant finish allows the pistol to better endure the effects of perspiration.

[11] The P99 features four internal safeties, iron sights adjustable for both windage and elevation, tool-less take down, and an ambidextrous magazine release incorporated into the trigger guard.

The lower forward edge of the frame also known as the dust cover has a mounting-bracket or rail interface system for attaching accessories, such as a tactical light or laser sight.

The .40 S&W caliber models incorporate a slightly larger slide in order to preserve the same recoil spring assembly used in its 9mm counterpart.

[citation needed] Compact versions of the P99 available in the 3 preceding action types marketed as the: The P99RAM is a training and simulation pistol, equipped with a CO2 blow-back system.

Walther has also created several limited production runs of the P99 including: The P99 RAD variant is made under license by Fabryka Broni Radom in Poland and marketed as a military sidearm proposition.

The grip frame has an integrated mounting MIL-STD-1913 (Picatinny) rail for attaching tactical lights and laser sighting devices.

[21] The P99Q has a partially pre-loaded internal striker trigger mechanism that conforms to the Technical Specifications (TR) of the German Police.

The grip frame has an integrated mounting MIL-STD-1913 (Picatinny) rail for attaching tactical lights and laser sighting devices.

[24] Magazines can be interchanged between the two models, but the pistols are considered to be two separate types, and are easily distinguished from each other by the trigger guard, grip and slide design.

The Magnum Research MR Eagle was another joint American/German venture, with Walther producing a black polymer frame with integral steel rails similar to the P99 series, only differing in grip texture and with the short magazine release paddles from the first gen P99.