A polymeric revolver including a frame, a cylinder mounted in a rectangular aperture in the frame, a cylinder retaining mechanism and a cylinder releasing mechanism is provided. The cylinder retaining mechanism includes two assemblies: (1) an extractor, locking bolt and locking bolt retainer that house an extractor rod spring, and (2) a ratchet hub driver, hub drive center pin and central pin plate that house a ratchet drive spring. The two assemblies are biased toward one another forming a locking engagement of the extractor and the ratchet hub driver. The locking engagement is enhanced by a star-shaped configuration of grooves and ridges on the extractor and ratchet hub driver, respectively. The cylinder releasing mechanism includes a cylinder release lever that actuates the hub drive center pin and ratchet hub driver out of locking engagement with the extractor, and an ambidextrous thumb piece that facilitates access to the cylinder release lever.