One Horse Complete AR-15 Upper Receiver - 5.56 - 10.5"

The One Horse Complete AR-15 Upper Receiver in 5.56 NATO pairs a 10.5" medium profile 4150 steel barrel with a 10" M-LOK free-float handguard, built to mil-spec standards in the USA.

Features:

• 10.5" medium profile 4150 steel barrel, nitride treated
• Carbine-length gas system
• 10" M-LOK free-float handguard, steel barrel nut
• Nitride bolt carrier group
• Standard charging handle (included)
• 1/2x28 threaded muzzle
• Made in the USA

4150 steel carries higher carbon content than the 4140 used in many entry-level AR-15 barrels, giving this barrel improved wear resistance at the bore and chamber under sustained firing, and the nitride treatment adds a hard, corrosion-resistant surface comparable to chrome lining without adding measurable thickness. The free-float M-LOK handguard keeps the barrel isolated from contact pressure that degrades harmonics, and the steel barrel nut gives a more rigid handguard-to-upper connection.