Volquartsen Firearms Reduced Pistol Recoil Spring Ruger MKII MKIII MK IV and 22/45. Specifications for Volquartsen Firearms Reduced Pistol Recoil Spring Ruger MKII MKIII MK IV 22/45: Manufacturer: Volquartsen Firearms Model: Reduced Recoil Spring Gun Make: Ruger Gun Model: Ruger Mark IV Ruger Mark III Ruger Mark II Caliber: .22 Long Rifle Country of Origin: USA Features of Volquartsen Firearms Reduced Pistol Recoil Spring Ruger MKII MKIII MK IV 22/45 This spring is designed only for use with the recoil rod packaged in our kit Package Contents: Volquartsen Firearms Reduced Pistol Recoil Spring Ruger MKII MKIII MK IV 22/45 What firearm models does the manufacturer say Volquartsen Firearms Reduced Pistol Recoil Spring Ruger MKII MKIII MK IV 22/45 is compatible with? The manufacturer suggests that Volquartsen Firearms Reduced Pistol Recoil Spring Ruger MKII MKIII MK IV 22/45 is compatible with Ruger Mark II Ruger Mark III Ruger Mark IVVolquartsen Firearms VC3RSO-R: Reduced Pistol Recoil Spring Ruger MKII MKIII MK IV and 22/45