The half cock function allows the loading gate to open and makes sure the chambers will line up with the loading gate. Provides 3 positive clicks when hammer is cocked. Minor fitting is required for proper installation.Notes:Trigger pull should weigh 2 1/4lbs with the Wolff reduced power spring kit and approx. 3 to 31/4 lbs with the factory springs. This hammer and trigger kit is compatible with both the New (small frame) and Old-Style Ruger Vaquero models.