US Patent 10156409 Trigger mechanism for firearm

A trigger mechanism has a first trigger which engages a sear connector and a second trigger, pivotably mounted on the first trigger, which supports the sear connector. The sear connector supports a sear, which holds a firing pin in the cocked position via a cocking piece. To discharge the firearm both triggers must be pulled. A safety lever has a hook which engages the second trigger and a projection which engages a spur on the first trigger when the lever is in the safe position.