Colt M4 to M5 Carbine Upper Reciever Kit in 5.56 Nato 14.5 in. Heavy Barrel Black - Front View
Colt M4 to M5 Carbine Upper Reciever Kit in 5.56 Nato 16.1 in. Heavy Barrel Black - Front View
Colt M4 to M5 Carbine Upper Reciever Kit in 5.56 Nato 14.5 in. Heavy Barrel Black - Front View
Colt M4 to M5 Carbine Upper Reciever Kit in 5.56 Nato 16.1 in. Heavy Barrel Black - Front View

Colt M4 to M5 Carbine Upper Reciever Kit

$1,125.99
$1,125.99
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Style: 5.56 Nato 14.5 in. Heavy Barrel Black

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Reach is wasted if the upper cannot hold zero.

This kit upgrades a legacy M4 lower with a complete 5.56 NATO upper in 14.5-inch or 16.1-inch chrome-lined heavy barrel, a one-piece M-LOK handguard, and a continuous MIL-STD-1913 top rail.

Performance Under Pressure: You run the carbine-length direct impingement system, then use the folding iron sights or an optic on the full rail when the distance is not known.

Durability and Reliability: Improved barrel retention, a Colt low-profile pinned gas block, and a 1:7 twist keep the heavy barrel honest under heat and sling load.

Friction Removal: An ambidextrous Radian Raptor charging handle and folding sights arrive with the upper, so the conversion is a mate-up, not a scavenger hunt.

Identity Signal: A free-float carbine upper on a legacy M4 lower looks like a current working rifle, not a leftover issue gun.

Proof and Credibility: Compatible with Colt M4 and legacy M4 lower receivers. Chambered in 5.56 NATO as a complete upper receiver assembly.

Choose the barrel length and keep the same rigid upper.