The Daniel Defense MK12 SPR upper receiver group (brand part no. 23-142-10035) is a complete 5.56 NATO upper built around an 18-inch cold hammer forged stainless steel barrel with a 1:7 twist and the MK12 profile. Daniel Defense pairs the barrel with a rifle-length direct impingement gas system, the MK12 gas block built to Crane specifications, a 12-inch free-floating Picatinny quad rail and its own flash suppressor. A mil-spec receiver with M4 feed ramps, an M16 profile bolt carrier group and an ambidextrous charging handle complete the group. It ships without sights, so the optic is your choice, and it suits a builder chasing a designated-marksman style rifle.

Key Specifications

• The chambering is 5.56 NATO, the cartridge the MK12 platform is known for.
• Barrel length is 18 inches, long enough to extract more velocity from 5.56 for precision work.
• The barrel is stainless steel and cold hammer forged, with the chamber created in the forging process.
• Rate of twist is 1:7, which stabilizes heavier bullets used at longer range.
• The profile is the MK12 barrel profile, the contour Daniel Defense uses for this designated-marksman layout.
• The gas system is a rifle-length direct impingement design, which gives a smoother cycle on an 18-inch barrel.
• The MK12 gas block is built to Crane (Naval Surface Warfare Center) specifications for USSOCOM.
• The handguard is a 12-inch free-floating Picatinny quad rail, which leaves the barrel free of hand pressure and gives room for accessories.
• The muzzle device is a Daniel Defense flash suppressor in 17-4 PH stainless steel with a salt bath nitride finish.
• The receiver is 7075-T6 aluminum, Type III hard coat anodized, with mil-spec indexing marks and M4 feed ramps, and an M16 profile bolt carrier group and ambidextrous charging handle come with the group.

Frequently Asked Questions

Does this upper include sights? No. It ships with no sights installed, so you add the optic or backup sights of your choice.

What gas system does it use? It uses a rifle-length direct impingement gas system with the MK12 gas block, matched to the 18-inch barrel.

Is the bolt carrier group included? Yes. Daniel Defense complete upper receiver groups come with an M16 profile bolt carrier group and an ambidextrous charging handle.

Buy the Daniel Defense MK12 SPR Upper Receiver Group, 5.56 NATO, 18-Inch

An 18-inch stainless barrel, a free-floating rail and a complete bolt group make this a ready-to-run upper for a precision AR-15 build. Order it from our Lubbock, Texas gun shop for fast direct shipping, and see more ar15 uppers.