The Daniel Defense MK12 Is The Crown
Jewel Of The Squad Designated
In 2004, at the height of the Iraqi Freedom campaign, the United States Army decided to develop a program to produce specialized marksmen for engaging targets at ranges beyond routine training distances.
With training resources invested in other areas, the Army, Marksmanship Unit (AMU)—in concert with the Civilian Marksmanship Program (CMP)—sought out a small cadre of volunteers from the Distinguished Rifleman Badge holders of NRA High Power competition.
They met in San Antonio and designed an initial Squad Designated Marksman (SDM) program that kicked off at nearby Camp Bullis, training 80 soldiers from the First Cavalry Division at Ft. Hood, Texas. The trainees included cooks, scouts and tank drivers. They would be assigned to security and patrol duties in Iraq.
Subsequently, five or six volunteers went to various combat units to administer the training stateside. The “official” rifle of these early beginnings was the M14. Later, as the Army took over the program, the official SDM rifle became the standard AMU match AR rifle with ACOG sight, firing Black Hills 77-grain BTHP (the Department of Defense is now loading a similar round). In practice, the AMU/CMP program trained the troops with whatever they brought to the party—frequently standard M4’s.
Local Distinguished Rifleman Badge holder, Stan Jarosz assisted with the classes at Camp Bullis and is recognized by the Army for his contributions. Additionally, he regularly trains young shooters on their way to the National Matches at Camp Perry and manages local Service Rifle Matches. Very much a devotee of cutting-edge small arms development, Stan was very interested in the new MK12 and volunteered his personal range and shooting skills to check it out.
The private range of Stan Jarosz was used for all intermediate
range testing. Stan’s group trained US Army Designated Marksman
troops out to 500 yards.
The MK12 is designed to bridge the performance gap between the standard-issue M4 and dedicated long-range “sniper” rifles. The MK12 is of the flat-receiver type, consisting of Daniel Defense peripherals wrapped around their MK12-profile barrel, free-floated in a 12-inch accessory rail. The barrel is of stainless steel, hammer forged in-house. It is contiguous with the chamber and given the salt-bath nitride treatment—a process predicted to provide a barrel life of 20,000 rounds.
Although the Designated Marksman Package included an earlier Daniel Defense rifle with a Leupold 4 LR/T 3.5-10x40mm, we gilded the lily a bit by using the Leupold Mk 4 4.5-14×50, 30mm Long-Range Tactical Sight with Tactical Milling Reticle. This is a rugged, side-focusing optic with 100 MOA of adjustment. It is suitable for the most demanding intermediate and long-range situations and the reticle provides quick and dirty range estimation. The instrument has enough vertical adjustment to move from a 100-yard zero to dead-on at 1,000 with both standard service rounds.
We found the second major crosshair from the bottom was sufficient for our 500-yard shooting with either Hornady BTHP match loads or the Black Hills load featuring the 69-grain Sierra MatchKing. It was not necessary to employ the turret adjustments. With the center crosshair zeroed for 100 yards, the Black Hills load was about 15 inches low at 300, corresponding closely with the first large crosshair down from center. The point of impact at 500 yards is 77 inches low with the third (large) crosshair down making a usable point of aim.
Stan Jarosz has the expertise to produce groups like
this one shot at 500 yards with Black Hills .223 ammo
loaded with the Sierra MatchKing 69-grain bullet.
Loads tested range from 55- to 62-grain defensive/LE rounds
designed for limited penetration to the long-range heavyweights.
The MK12’s 1:7-inch twist barrel turned in excellent results
across the spectrum.
Daniel Defense has been getting 1/2- to 3/4-inch groups in house with a variety of loads, the 1:7-inch twist being optimal for the heavier weight bullets. When shooting accurate rifles, my default group appears to be 1.1 inches at 100 yards—some better, some worse. With the MK12, this is what I frequently got regardless of the load or bullet weight. Whether the five rounds landed in the sub-minute range, 1.1-inch spread or somewhat larger, virtually all of my bench-rested efforts put four of the five in spreads ranging from 1/2 to 1 minute.
The 20-round magazine supplied is better adapted for benchrest shooting and field use than the 30-round standard mag. The Geissele trigger is the same high-end unit the company uses on the Ambush Carbine. It has a short first stage and breaks at 4 pounds after perceptible second-stage take-up.
Everything about it suited me right down to the ground, but Stan Jarosz deplored the creep in the second stage, preferring the totally crisp release of his other match triggers. Like other light AR triggers, the Geissele needs a firm shooting grip for best function. Larry Cohen finessed the trigger after the fashion of benchrest and hunter-rifle competitors, applying essentially no resistance to the pistol grip, and produced a pair of consecutive 2-round bursts for his pains!
Stan had one similar event—an inadvertent full-buzz burst playing hob with 200-yard groups. But when handled conventionally—with a firm grip—the MK12 was completely reliable with all loads.
We benched the MK12 from 200, 300 and 500 yards, using primarily the 69-grain Black Hills load and the Hornady 75-grain Superformance Match and BTHP loads, which were virtually identical in accuracy and downrange performance. Stan and I swapped off shooting 5-round groups and getting essentially the same results at 200 and 300 yards. At 500 yards, Stan turned in the better performance—not unexpected considering his credentials. We were dealing with a fairly steady 4 mph crosswind and significant heat mirage at 14X magnification. Our aiming points were 3-inch Birchwood-Casey target pasties and the Tactical Milling Reticle made it easy to define them at distance. The Leupold, incidentally, is also available with a mil-dot reticle at a lower price. The dot arrangement might be more user-friendly for artificial light shooting, as the TMR is a bit tedious to pick up, with the reduced contrast being a factor with green laser designators.
Our results indicated a trend toward 5-round groups of slightly over 1-MOA with four of the five rounds grouping in half to just under a full MOA. As with my 100-yard groups, it appeared that some of the first, hand-cycled rounds might be hitting slightly away from the main group, but control groups—excluding the first and last rounds in the magazine—produced no clear proof of this.
The Daniel Defense MK12 fills the gap between the basic service rifle and long-range sniper systems. It incorporates Daniel Defense components with a simultaneously hammer-forged barrel and chamber of stainless steel with salt bath nitride finish. The lower receiver is mil-spec with flared magazine well, CNC-machined of 7075-T6 Aluminum and hard anodized. The 20-round magazine is compatible with field-expedient rests. At 7.4 pounds plus 22 ounces for the scope, the MK12 is reasonably comfortable when carried with the Blue Force Vickers sling.
Stan got a couple of wickedly effective groups from 500 yards and then shot for the record on a TXTP/ B27 target with the same result. He deemed the MK12 equipped with the Leupold LRT a very suitable DM rifle.
Shooting standing at 100 yards with the magnification dialed back for favorable field of view and eye relief, the MK12 performed up to expectations for a basic AR-15 with a user-friendly trigger. Twenty rounds fired in 5-round strings made the heavy-profile barrel a bit warm to the touch, but by no means uncomfortable.
The BCM Gunfighter charging handle is easy to manipulate underneath the scope and the proprietary DD grip and cheekpiece were comfortable and attractive. I used RIG synthetic oil for preliminary lubrication of the bolt and bolt carrier and applied RIG Liquid Gun Grease to the lockwork. Although called a “liquid,” it is still more viscous than light machine oil and had good staying power. Cleaning with RIG copper solvent after several shooting sessions revealed quite a bit of residue in the barrel and chamber, but no blue tint on the patches that would indicate significant copper buildup.
Law enforcement agencies, SWAT Teams, SOCOM and International Special Operations Units use Daniel Defense products as standard equipment.
The MK12 is currently the company’s state-of-the-art AR and rides on top of the pricing structure. Daniel Defense offers a range of products covering every practical variation on the AR/Stoner system and is widely respected in official circles and among discerning private users.
By Mike Cumpston
Maker: Daniel Defense, Inc.
101 Warfighter Way
Black Creek, GA 31308
Action: Direct-gas impingement semi-auto
Barrel length: 18 inches
Twist: 1:7 inches
Overall length: 34-3/4 inches, 37-7/8 inches extended
Weight: 7.41 pounds
Sights: None, Picatinny rail provided
Stock: Daniel Defense telescoping
Mark 4 LR/T 4.5-14x50mm
Maker: Leupold & Stevens
14400 Northwest Greenbriar Parkway
Beaverton, OR, 97006
Objective Diameter: 2.3 inches
Eye Relief: 3.6-4.5 inches
Internal Adjustment Range: 100 MOA elevation and windage (100 yards)
Click Value: 1/4 inch
Tube Diameter: 30mm, Weight: 22 ounces
Overall Length: 12.5 inches. Reticle: TMR
7900 Fuller Road
Eden Prairie, MN 55344
Black Hills Ammunition
PO Box 3090
Rapid City, SD 57709
Blue Force Gear, Inc.
P.O. Box 853
Pooler, GA 31322
3625 West Old Potash Hwy.
Grand Island, NE 68803
107 SW Columbia St., Bend, OR 97702
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