Patent ID: 8464453

Claim:
A firearm upper receiver assembly comprising: a. a modified upper receiver having an interior surface defining an interior chamber, a longitudinal forward region having a barrel mounting portion, a longitudinal rearward region comprising a surface defining a spring guide passage, an upper region having a surface defining a charge handle passage; b. a bolt having a slide fit with the interior surface of the upper receiver, the bolt comprising a surface defining a firing pin—passageway, a rimfire firing pin movably positioned to move a prescribed amount of distance within the firing pin passageway, the bolt having a longitudinally forward region with a bolt surface, the bolt having an upper region having a charge handle engagement surface, the bolt further having a surface defining a recoil guide rod chamber; c. a charge handle having a slide fit with the charge handle passage of the upper receiver, the charge handle having a bolt engagement feature positioned to engage the charge handle engagement surface of the bolt wherein the charge handle is configured to reposition the bolt in a longitudinal rearward direction with respect to the upper receiver and further the bolt can reposition longitudinally rearwardly and forwardly without movement of the charge handle when the charge handle is in a longitudinally forward orientation with respect to the upper receiver; d. a recoil spring guide coupled to a longitudinal rearward portion of the upper receiver where the recoil spring guide rod passes through the surface defining a recoil guide rod chamber within the bolt; e. a backer plate in slide fit engagement with the longitudinal rearward region of the interior chamber of the upper receiver and fastened thereto; f. wherein the recoil spring guide is positionable relative to the backer plate; g. a threaded retaining plug is threadedly attached to a threaded recess in the upper receiver, wherein the threaded recess is coaxial to the recoil spring guide, wherein the rearward end of the recoil spring guide is retained within the retaining plug; and h. wherein the recoil spring guide is removably coupled to the backer plate.