The Colt LE6921 5.56 NATO upper receiver assembly is a battle-proven complete upper built to the exacting specs that have made Colt's military and law enforcement rifles the gold standard. This 14.5-inch upper comes fully assembled with bolt carrier group and charging handle — everything you need to marry it to a compatible lower and get a functioning rifle. Whether you're building a short-stroke patrol rifle or need a compact upper for an existing Colt platform, the LE6921 delivers the reliability Colt is known for in a configuration that balances maneuverability with enough barrel length to stabilize 5.56 rounds downrange.

The barrel is chrome-lined for durability and longevity, a feature that matters if you plan to run volume through the gun. A 1-in-7 right-hand twist stabilizes a wide range of 5.56 ammunition loads, from lighter training rounds to heavier match or defensive ammunition. The flat-top receiver gives you flexibility to mount optics the way modern shooters prefer, while the included flip-up rear sight provides a reliable mechanical backup. The bayonet lug harks back to Colt's military lineage — whether you use it or not, it's there if you need it.

One important note: this upper ships with a pivot pin adapter to fit Colt lower receivers that use large pivot pins. The bolt carrier assembly is current production and may not be compatible with some older Colt rifles equipped with a steel sear block, so verify compatibility with your lower if you're pairing this with a vintage receiver. The included screw-on flash hider helps manage muzzle blast and signature in shorter configurations.

The Colt LE6921 5.56 NATO upper receiver assembly is a battle-proven complete upper built to the exacting specs that have made Colt's military and law enforcement rifles the gold standard. This 14.5-inch upper comes fully assembled with bolt carrier group and charging handle — everything you need to marry it to a compatible lower and get a functioning rifle. Whether you're building a short-stroke patrol rifle or need a compact upper for an existing Colt platform, the LE6921 delivers the reliability Colt is known for in a configuration that balances maneuverability with enough barrel length to stabilize 5.56 rounds downrange.

The barrel is chrome-lined for durability and longevity, a feature that matters if you plan to run volume through the gun. A 1-in-7 right-hand twist stabilizes a wide range of 5.56 ammunition loads, from lighter training rounds to heavier match or defensive ammunition. The flat-top receiver gives you flexibility to mount optics the way modern shooters prefer, while the included flip-up rear sight provides a reliable mechanical backup. The bayonet lug harks back to Colt's military lineage — whether you use it or not, it's there if you need it.

One important note: this upper ships with a pivot pin adapter to fit Colt lower receivers that use large pivot pins. The bolt carrier assembly is current production and may not be compatible with some older Colt rifles equipped with a steel sear block, so verify compatibility with your lower if you're pairing this with a vintage receiver. The included screw-on flash hider helps manage muzzle blast and signature in shorter configurations.