The Spike’s Tactical ST-15 Enhanced Complete Upper (brand part number STU5435R2S) brings a fully mil-spec-compliant AR-15 upper, originally designed for law enforcement, to shooters at a price point that fits any budget. Every component on this upper is manufactured to mil-spec standards, starting with a 16-inch, 1:7-twist, cold hammer-forged barrel finished in black phosphate and cut with a mid-length gas system for smoother cycling and reduced felt recoil. The build includes Spike’s ST Optimum Profile barrel contour, an ST Micro gas block on a .750-inch diameter gas seat, and a Spike’s mil-spec M16 bolt carrier group for reliable, full-auto-rated cycling. Rounding out the package is a 12-inch ST BAR2 free-floating handguard and an A2 flash hider, giving builders a complete, ready-to-run upper for a compatible AR-15 lower.

Key Specifications

• Chambered in 5.56x45mm NATO/.223 Remington.
• Barrel length is 16 inches, cold hammer-forged to mil-spec standards.
• Rifling twist rate is 1:7 inches.
• Barrel is finished in black phosphate and cut in Spike’s ST Optimum Profile.
• Runs a mid-length gas system for smoother cycling and reduced felt recoil.
• Includes an ST Micro gas block on a .750-inch diameter gas seat.
• Comes with a Spike’s mil-spec M16 bolt carrier group.
• Features a 12-inch ST BAR2 free-floating handguard.
• Topped with an A2 flash hider and left optic-ready with no iron sights included.
• Receiver is machined from 7075-T6 aluminum and finished in black.

Frequently Asked Questions

Does this upper include a bolt carrier group? Yes, a Spike’s mil-spec M16 bolt carrier group is included with the complete upper.

What gas system does this upper run? A mid-length gas system, which tends to run smoother and with less felt recoil than a carbine-length system.

Does this upper include iron sights? No, it ships optic-ready with no sights included.

Buy the Spike’s Tactical ST-15 Enhanced Complete Upper

Order the Spike’s ST-15 Enhanced complete upper from our Lubbock, Texas gun shop for fast, insured shipping. See more Spike’s Tactical AR15 uppers for your build.