M16A1 Steel Front Set Assembly|M16A1 鋼製前段總成
XM177E2 Steel Front Set Assembly|XM177E2 鋼製前段總成
XM177E1 Steel Front Set Assembly|XM177E1 鋼製前段總成
M16A2 Steel Front Set Assembly|M16A2 鋼製前段總成
M4A1 Steel Front Set Assembly|M4A1 鋼製前段總成
Barrel Extension|槍膛座