The P22 is a semi-automatic pistol manufactured by Carl Walther GmbH Sportwaffen.
On the exterior, it resembles the Walther P99, but it is somewhat smaller (75% of the P99's size) and its action chambers the rimfire .22 LR cartridge. The most noticeable exterior difference is the P22's slide mounted, thumb operated, ambidextrous safety and its external hammer. The P22 features a cast polymer grip-frame. Its slide and serial numbered frame receiver inserts are made from MIM (Metal Injection Molding) cast zinc alloy, its barrel consists of a rifled steel insert within a steel barrel sleeve, and its internal lockwork and fire-control parts are a combination of MIM cast steel and steel stampings.
The P22 can be purchased with a 3.4-inch short barrel (pictured to the right), or with a 5-inch barrel which includes a barrel mounted weight compensator matching the profile of the slide. The P22 was originally designed such that the two different length barrel assemblies could be easily interchanged, and "combo" packages including both barrels were offered for sale.
The P22 is offered in many different color variations of its polymer lower receiver. The pistol is available in black, olive drab, grey, carbon fiber and 3 pink versions. There is now a new lower receiver finish that looks like Damascus steel. The slide assembly will have either a blue-black applied finish or it will be finished with a nickel/stainless look. Along with the new finish for the lower receiver, the slide also has a new finish option of brushed stainless.
The production year is located on the receiver and is visible through the ejection port when the slide is closed. The year is indicated with a two letter code where A=0, B=1, C=2 and so on to I=8 and K=9 ("J" is never used as a year designator). In the image you can see the receiver is labeled with AH indicating a production year of 07.
There are three revisions of the Walther P22 magazine as the original design was prone to feed failures. Walther corrected the issue by modifying the feed ears and adding a short 3/8" slot which allows rounds to stagger as they approach the top of the magazine. The second version of the magazine is designated with an "A" after the part number. Later versions of the "A" magazine have an elongated 1" stagger slot which further improves the magazine's performance. Finally Walther has released a "B" version which is made of thicker steel, has a tall spring retaining nub and retains the 1" stagger slot.
The P22 may be fired double action at about 12 pounds of force, and operates as a single action with slightly more than 5 pounds of force. The P22 operates by blowback where pressure generated by a firing cartridge is countered by a combination of the inertial weight of the slide assembly and the force of the recoil spring. The action will not open until the projectile has left the barrel and the pressures have dropped to safe levels.
The P22 is equipped with a magazine disconnect that prevents the trigger from operating on the sear mechanism unless a magazine is actually inserted and locked into the weapon. The magazine disconnect on a P22 works by using a strong spring to apply downward force against the trigger bar, such force being sufficient to overcome the action of the relatively weaker trigger spring which interacts with upward force on the same bar. When a magazine is not locked into the weapon, the downward force of the stronger magazine disconnect spring causes the trigger bar to pass beneath the internal lockwork of the weapon when the trigger is pressed. Once a magazine is fully inserted, however, an actuator surface on the front of the magazine pushes against the magazine safety. This overcomes the magazine safety's strong spring, and thereby serves to allow the trigger bar to spring upward under the force of the less powerful trigger spring. When this occurs, the trigger bar is in a position where it engages the lockwork when the trigger is actuated.
Walther recommends the use of high velocity 22 Long Rifle cartridge and reportedly tests with CCI Mini Mag round nose coated lead.
The P22's slide mounted safety, when engaged, performs two functions. First, it serves as a "hammer block" by rotating a portion of the metal surface of the safety into a position that interferes with the hammer's contact with the firing pin. Second, it acts as a "firing pin lock" by rotating a portion of the safety into a notch on the underside of the firing pin, thereby inhibiting forward movement. The P22 safety does not prevent sear or trigger movement, and (as noted), it does not provide a hammer-drop function. If the hammer is cocked when a P22 has been placed on "safe", the hammer will continue to remain cocked and will fall only if the trigger is pressed. If the safety is on, the hammer will strike the safety instead of the firing pin and, therefore, fail to fire.
The P22 uses an additional, passive, safety mechanism to protect against accidental discharges in the event the weapon is dropped. When the action is closed, a small metal button on the underside of the breech block is actuated by an arm surface extending from the sear. In this state (whether or not the hammer is cocked), the firing pin is mechanically blocked and cannot move forward to strike a cartridge rim. When the trigger is pressed, the sear moves downward in such a way as to move from its interaction with the firing pin safety, which in turn springs downward under the force of a captive spring within the breech block. This disengages the firing pin safety, allowing the firing pin to move and the weapon to fire.