Patent ID: 8479429

Claim:
A firearm with spring-loaded barrel retaining system comprising: a receiver; a barrel nut coupled to the receiver and defining a first radial spring seating surface; a barrel assembly rotatably coupled to the barrel nut and defining a longitudinal axis, a forward muzzle end, and an opposite rearward breech end, the barrel assembly defining a second radial spring seating surface; and a spring member operably engaging the first and second radial spring seating surfaces, the spring member biasing the barrel assembly in a forward direction away from the barrel nut; wherein the barrel nut further includes a plurality of longitudinally-extending splines configured and arranged to rotatably engage a plurality of barrel locking lugs disposed on the barrel assembly, the barrel assembly being axially slidable into the barrel nut, wherein the splines and locking lugs are arranged so that when the barrel assembly is slid into the barrel nut and rotated into a locked position, the barrel assembly cannot be axially withdrawn from the barrel nut.