Trigger group for semi-automatic firearms

A trigger assembly for a firearm comprising:

• a frame;
• a hammer connected to the frame and movable between a cocked position and a striking position;
• the hammer being biased toward the striking position;
• a trigger element connected to the frame and movable by a user between a forward position and a rearward position;
• a single selector connected to the frame and movable between at least a safe position, a first position, and a second position;
• a disconnector assembly having a hammer engagement facility adapted to selectably engage the hammer;
• the disconnector assembly having a disconnector spacer moveable between at least a first condition being held disengaged by the hammer and a second position being engaged;
• the disconnector assembly movable between a first control condition and a second control condition;
• the disconnector assembly operable to move in a first range of motion when in a first control condition;
• and
• the disconnector assembly operable to move in a shorter range of motion different from the first range of motion when in a second control condition, such that the trigger assembly operates in a first mode when the selector is in the first position, and in a second mode when in the second position.