All Mark IV pistols including 22/45 models manufactured prior to June 1, 2017 have the potential to discharge unintentionally if the safety is not utilized correctly. In particular, if the trigger is pulled while the safety lever is midway between the "safe" and "fire" positions (that is, the safety is not fully engaged or fully disengaged), then the pistol may not fire when the trigger is pulled. However, if the trigger is released and the safety lever is then moved from the mid position to the "fire" position, the pistol may fire at that time.
All Mark IV™ pistols produced prior to June 1, 2017 are potentially affected and therefore are being recalled. This includes Mark IV™ Target, Hunter, Competition, 22/45™, 22/45™ Lite and 22/45™ Tactical models. These models bear serial numbers beginning with "401" (2017 models) or "WBR" (2016 models).
Newly manufactured Mark IV™ pistols will begin with serial number "500." Thus, if you have a Mark IV™ or 22/45™ pistol with a serial number beginning with the number "5," your pistol is not subject to the recall.
Mark IV™ and 22/45™ pistols retrofitted with the updated safety mechanism are easily identified by the letter "S" in the white safety dot that is visible when the safety is engaged.
We only want the grip frame assembly. It is not necessary for us to have the barrel/receiver assembly to perform the retrofit. Because the barrel/receiver assembly is the serialized component, not requiring its return simplifies the process and will enable us to more conveniently and quickly return the grip frame assembly to you. Please follow the instructions in your instruction manual to separate the barrel/receiver assembly from the grip frame assembly. Keep the barrel/receiver assembly, magazines, lock, instruction manual, and any aftermarket accessories. When we send you the box and shipping label, we will also send detailed instructions describing what we want you to send and how to send it.
https://ruger.com/MarkIVRecall