A Swan universal receiver sleeve attached to the top of a firearm upper receiver and extended forward above the firearm barrel to a position just short of the firearm front sight. The underside of the rear portion of the sleeve is fixedly attached to the receiver top. The underside of the forward portion of the sleeve has an upper handguard piece attached thereto. A bottom handguard piece is fitted about the bottom of the gun barrel and is attached to the upper handguard piece. The handguard pieces are not physically connected in any way to the gun barrel. The sleeve is self supported by the connection of the rear portion underside to the receiver top. A special yoke is inserted about the barrel nut of the firearm to which the modular sleeve is attached. The special yoke reinforces the modular sleeve while keeping the firearm barrel free floating.