SKU: 99736
UPC: 815648021320
MPN: STU5035S2S
The Spikes STU5035S2S Complete Upper in 5.56x45mm NATO is a ready-to-run upper receiver assembly designed for shooters who demand reliability without compromise. Built for law enforcement, military personnel, and serious civilian marksmen, this complete upper eliminates the guesswork of component sourcing and delivers a matched, tested platform straight out of the box. Whether you're building a duty rifle, a precision carbine, or a home-defense platform, this upper provides the foundation for a dependable 5.56 NATO system.
Manufactured from 7075-T6 aluminum, the receiver achieves industry-leading strength-to-weight ratio—critical for extended patrol or tactical operations where fatigue compounds shooting error. The 16-inch black phosphate barrel offers the optimal balance between velocity, handling, and sight radius for close-quarters and mid-range engagements; black phosphate finish provides rust resistance and a low-reflective surface. The 12-inch SAR3 free-floating handguard decouples from the barrel, eliminating harmonic vibration and improving shot grouping consistency—a feature LEOs and precision shooters value equally. At 4.9 pounds, the upper maintains a forward-balanced profile that reduces muzzle rise and accelerates target reacquisition in rapid-fire sequences.
This complete upper is fully compatible with standard AR-15 lower receivers (both mil-spec and commercial), making it adaptable to patrol rifles, recce platforms, or SBR builds with appropriate lower configuration. Installation requires only standard AR takedown pins—no gunsmithing necessary. The midlength gas system strikes the ideal compromise between reliability and controllability, especially when paired with quality carriers and buffers. Ideal for departments standardizing on 5.56 platforms, competitors seeking a no-hassle upgrade, or operators building modular multi-caliber arsenals.
WARNING ⚠️ You must be 18 or older to purchase shotgun or rifle ammunition and 21 or older to purchase handgun ammunition and firearms. Please reference our requirements for ammunition orders to "restricted" states HERE. Always make sure you use the correct ammunition for your firearms. Ammo cannot be shipped to a PO Box. Please reference state & local laws before making a firearm or ammunition purchase.
