A firearm comprising a frame, a barrel with a firing axis connected to the frame, a cylinder pivotally attached to the frame and positioned within an opening in the frame and having a plurality of firing chambers sized to receive a cartridge, and a firing mechanism including a trigger attached to the frame to actuate the firing mechanism, wherein the frame is substantially nonmetallic and includes at least one metal insert having a polymer over-molding. A cylinder retaining mechanism selectively retains the cylinder in a first position within a window in the frame and comprises a biasing pin operatively attached to a yoke and which is oriented in a direction substantially transverse to the bore axis when the cylinder is in the first position.