The Daniel Defense MK12 SPR Upper Receiver Group (brand part no. 23-142-10035) is a complete, 5.56 NATO chambered AR-15 upper built around an 18-inch barrel with a 1-in-7 twist rate, patterned after the Special Purpose Rifle configuration used by US special operations designated marksmen. The 1-in-7 twist stabilizes heavier, longer bullets suited to precision work at extended range, while the complete-style build means the upper arrives ready to mate to a compatible AR-15 lower without sourcing a barrel or bolt carrier group separately. It ships with no sights installed, so shooters can top it with the optic of their choice. At roughly 6.2 pounds shipping weight, it carries the heft typical of a barrel this length built for sustained accuracy rather than close-quarters maneuverability.

Key Specifications

• Chambered in 5.56 NATO / .223 Remington for broad ammunition compatibility.
• 18-inch barrel length suits designated-marksman-style precision shooting.
• 1-in-7 twist rate stabilizes heavier, longer-range 5.56 projectiles.
• Sold as a complete upper assembly, ready to mate to a compatible lower.
• Ships with no sights installed, leaving optic choice up to the shooter.
• Built to the MK12 SPR configuration favored for designated-marksman rifles.

Frequently Asked Questions

Does this upper include sights? No, it ships with no sights so you can mount your own optic.

What twist rate does this barrel use? A 1-in-7 twist, suited to heavier, longer-range 5.56 projectiles.

Is this a complete, ready-to-install upper? Yes, it is a complete upper receiver group that mates to a compatible AR-15 lower.

Buy the Daniel Defense MK12 SPR Upper

Build a designated-marksman-style AR-15 around the same barrel length and twist the MK12 SPR is known for. Order this Daniel Defense upper from our AR15 uppers selection, and our Lubbock, Texas team will get it shipped fast.