Parts Diagrams: Upper Receiver And Barrel Assembly 

Upper Receiver And Barrel Assembly

(1) Handguard Assembly
(2) Gas Tube Pin
(3) Gas Tube
(4) Flash Suppressor/Compensator
(5) Peel Washer
(6) Handguard Slip Ring Retaining Ring
(7) Handguard Slip Ring Spring
(8) Handguard Slip Ring
(9) Upper Receiver Assembly
(10) Barrel Assembly