A gas spring assembly is disposed within a compression chamber of an air gun, and includes a piston defining an interior pressure chamber. The piston includes a latch bushing that is disposed adjacent a rearward end of the bushing. The latch bushing defines a central bore that extends along and is concentric with a longitudinal axis of the piston. A guide rod is slideably supported within the central bore of the latch bushing. The piston is axially moveable along the longitudinal axis relative to the guide rod, between a compressed position and an un-compressed position. The guide rod includes a first end that engages the trigger assembly in abutting engagement, and a second end that engages a head portion disposed within an inner support tube within the interior pressure chamber of the piston. The latch bushing includes a ledge for engaging a sear of the trigger assembly in latching engagement.