Delta Ring Assembly (A2 Type)|星狀環總成 (A2 型式)
M16 / M16A1 20 inch Steel Outer Barrel|M16 / M16A1 20 吋鋼製外管
M653 SPORT 16 inch Steel Outer Barrel|M653 SPORT 16 吋鋼製外管
M653 14.5 inch Steel Outer Barrel|M653 14.5 吋鋼製外管
XM177E2 11.5 inch Steel Outer Barrel|XM177E2 11.5 吋鋼製外管
XM177E1 10.5 inch Steel Outer Barrel|XM177E1 10.5 吋鋼製外管