US Patent 10386149 Firearm system

A firearm system capable of easily attaching and detaching an upper receiver and a barrel is disclosed. The upper receiver is operably coupled to a bearing case. A plurality of bearings are positioned on the bearing case for engaging dimpled slots on the surface of the barrel. A spring sleeve is engageable with the biasing member and circumscribes the bearing case, biasing member and bearings. A dust cover is engageable with the spring sleeve. In an engaged state, the bearing case, the spring sleeve, and the dust cover are assembled such that the upper receiver and barrel are substantially aligned.