A factory-new, 100% Colt complete M16A4 flat-top upper receiver group with 20" barrel, bolt carrier group, and charging handle — Colt P/N M16A4-SUR, the current-issue USMC/USAF service-rifle upper.
The M16A4 is the 20-inch flat-top successor to the fixed-carry-handle M16A2 — adopted by the Marine Corps as the infantry service rifle in the early 2000s and fielded alongside the M4 carbine through the GWOT. Defining features are the full-length A2 profile 20" 1/7 chrome-lined barrel (heavy under the handguard, A2 profile at the gas block forward), the flat-top A4 upper with removable carry handle or optic-ready Picatinny, and the KAC M5 RAS rail system that was issued with many A4 builds. This upper ships without the rail — it gives the clone builder the correct Colt barrel and receiver to drop a period-correct RAS, KAC carry handle, or optic mount onto.
Colt ships these as factory-assembled uppers pulled from complete M16A4 rifles. The package includes Colt's own bolt carrier group and charging handle — both commonly missing from competitor "complete" uppers at this price. The stock photo typically shows the barreled receiver only, but the BCG and CH are in the box. The upper arrives in military-grade plastic with Colt's factory preservation oil on the barrel, receiver, and BCG, in a non-factory shipping carton.
Forge-mark variation is normal. Colt sources forgings from multiple suppliers (Cerro Forge, Brass Aluminum Forging Enterprises) and the mark on the magazine well will be one or the other — both are genuine Colt-production receivers. Charlie's cannot pre-select a forge mark.
We keep these in stock when we can. If you are building a clone-correct M16A4 or a true A4-pattern civilian 20", this is the foundation the rest of the build hangs on. Add to cart and we'll get it out the door fast.
Note: stock pictures do not always show the BCG and charging handle, but both are included with every upper.
Potomac Armory