553-13 553 Buffer Base
553-16 553 Charging Handle
553-17-1 553 Bolt Catch Stopper
553-21 553 Automatic Firing Lock
553-26 553 Release Bar
553-28 553 Firing Pin
553-29 553 Hammer Fixed Set
553-32 553 Fire Control Pins
553-34 553 Automatic Firing Pawl
553-M-01 553 Magazine Spring & Follower
553-M-03 553 Magazine Feedlips & Gas Router
553-M-05 553 Magazine Lever Set
