Mk12 Mod 0 Clone
A Brief History of the Mk12
The Mk12 Mod 0 SPR was developed in the early 2000s by NSWC Crane Division as a designated marksman rifle (DMR) for U.S. Special Operations Forces. Born out of a need for a lightweight, accurate, semi-automatic rifle capable of extending effective 5.56mm engagement ranges beyond standard M4 carbines, the Mk12 was designed to fill the gap between a carbine and a sniper rifle.
Mk12 Mod 0 rifles were often assembled on existing M16A1 or M4A1 lowers and retained many standard M16 components, such as fixed A1/A2 stocks. The weapon offered sub-MOA accuracy and became a favorite among SEALs, Green Berets, and other SOCOM units in Iraq and Afghanistan.
The Original Specs
The part that makes the Mk12 Mod 0 is the upper receiver. Â
Like many new weapon systems, the Mk12 Mod 0 was born out of spare parts. With the evolution of the M16 and M4, the military had lots of M16A1 and M4A1 lowers lying around. These were repurposed when a new upper was configured. As such, many of the Mk12 Mod 0 lower receiver specs are consistent with those of the M16A1 rifle (typical) or M4A1 carbine.
The Mk12 Mod 0 was not complete without some standard accessories.
"Really Close" Clone Bill of Materials (~$2,515)
Unless you have access to a registered M16A1 or M4A1 machine gun lower, you will not be building a true Mk18 Mod 0 clone. Without a machine gun lower receiver (manufactured by Colt or Hydramatic), the following components will not be clone accurate:
- Lower Receiver: Even if the lower has the correct profile and markings, it will not be drilled for auto sear pin. Colt makes great stuff for the U.S. Military. The stuff they release to the consumer market is NOT the same quality. Its not that they have a different spec for the consumer market…they just release the stuff that doesn’t pass the government standards. If you buy a Colt part, you are probably buying a 3rd or 4th round reject. When it comes to the lower, you can try to find a Colt M4A1 or M16A1 lower, but it is not worth the $800-900 you will pay for a stripped non-NFA lower (in our opinion). If you are a die hard clone fanatic, happy hunting. Our Mk12 clones are geared toward the rational enthusiast.
- Trigger Group: Early variants of the SPR used a standard M16A1 FCG. Without a select fire receiver, you will not be building with a full auto fire control group and auto sear. If you acquire a machine gun lower, you can absolutely build with a full auto trigger group and auto sear. Given that the Mk12 was not designed for full auto fire, it adopted a match-grade semi-auto trigger group. Our Mk12 clones assume that you are working with a semi-auto setup.
- Safety Selector: Without a select fire trigger, there is no point of having a select fire safety selector, even if your trigger functions with one.
"Improved" Clone Bill of Materials (~$2,450)
Our “Improved” clone includes clone-appropriate upgrades to the following components:
- Bolt Carrier Group: We upgrade to our PBA Enhanced Phosphate BCG, which is built from Microbest components, is meticulously gauged to ensure efficiency, is built with Michiguns O.C.K.S., and includes Sprinco springs and rings (5-coil extractor spring, ejector spring, O-ring, and gas rings). The result is a super-efficient and robust BCG that will outperform the Mil-Spec Colt BCG.
- Buffer Spring: Sprinco springs are superior to Mil-Spec buffer springs. The springs are chrome silicon wire stock, heat treated, stress relieved, dual stage shot-peened (post winding), and impregnated with a re-micronized molybdenum disulfide formulation. The result is a spring that will outperform and outlast (by far) your typical Mil-Spec spring.
- Receiver Extension: We switch out the Colt receiver extension for a Brownells, only because we don’t need the Colt buffer spring in the Colt kit. This change is undetectable (still a 7075-T6 rifle tube) and happens to save you money.
- Pistol Grip: We upgrade the Mil-Spec A2 grip to an ERGO Suregrip. This is still clone-correct and greatly improves the ergonomics and handling of the weapon.
"Close Enough" Clone Bill of Materials (~2,240)
Our “Close Enough” BOM is visually equivalent to the “Really Close” Mk18 Mod 0 clone, but includes less expensive but spec-equivalent (or better) components, where possible. Nobody will look at this gun and be able to tell that it is not spec-perfect without full disassembly and a keen eye. The following components deviate from the true specs:
- Trigger Group: We move to the ALG (manufactured by Geissele) Quality Mil Spec (QMS) trigger. In our opinion, this trigger is far superior to the issued Colt trigger, but doesn’t come with a premium price tag; win-win.
- Bolt Carrier Group: Despite the lower cost, our change to the BCG is a significant upgrade. We upgrade to our PBA Enhanced Phosphate BCG, which is built from Microbest components, is meticulously gauged to ensure efficiency, is built with Michiguns O.C.K.S., and includes Sprinco springs and rings (5-coil extractor spring, ejector spring, O-ring, and gas rings). The result is a super-efficient and robust BCG that will outperform the Mil-Spec Colt BCG.
- Buttstock: We shift from the Colt A2 stock to a Brownells A2 stock. Again, you benefit from visual equivalence and better consumer reviews.
- Non-Colt Parts: We shift away from Colt branded parts to less-overpriced components for the buffer, buffer spring, pistol grip, LPK, and gas tube.  These swaps are undetectable and often come with a better reputation. Don’t be fooled by the name; Colt consumer products don’t always get the best reviews.
"Budget" Clone Bill of Materials (~$1,650)
Our “Budget” clone BOM shaves nearly $900 off the “Really Close” price tag. You can probably save more if you sacrifice the look of the handguard, but if it doesn’t look anything like the original, we wouldn’t call it a clone. For the Mk12 Mod 0, we can get you close enough that someone 15 feet away won’t be able to tell. We start with our “Close Enough” clone and swap out the following components:
- Upper Receiver: We shift from Colt to a BKF upper. Functionally, this is equivalent, but will lack the C mark. BKF makes superb low-cost components, so you are not sacrificing quality (in fact, you may find that BKF receivers have better fit and finish than the consumer grade Colt receivers). This swap saves you over $110.
- Muzzle Device: We switch to a standard A2 birdcage flash hider. This saves about $145. Note that this will not work with the Allen Engineering suppressor.
- Charging Handle: We move from the PRI Gas Buster to a Brownell’s Mil-Spec. This is still a forged 7075-T6 charging handle, but comes in over $75 cheaper.
- Lower Receiver: We move from the H&R M16A1 lower to a BKF M16A1 marked lower. Note that the profile of the lower is NOT technically M16A1 correct; only the markings are correct. The most obvious differences (i.e. visible from an assembled gun) are in the milling contours. The M16A1 differs from the M16A2 (and later) profile at the pivot pin lugs and the reinforcement of the buffer tube boss. It is worth noting that the milling contours were changed for a reason (increase strength); so going clone-accurate is more for bragging rights than for performance or durability. For a savings of over $70, these are subtleties that only a clone snob will scoff at. And out of all of the clone deviations in this build, this is probably not the one someone will linger on.
- Trigger: We switch from the Geissele SSA-E to the ALG (manufactured by Geissele) Quality Mil Spec (QMS) trigger. Its not as good as an SSA-E, but its a hell of a lot better than a standard Mil-Spec trigger.
- LPK: We switch from the CMMG kit used in our “Close Enough” clone to an ALG LPK. This change is probably an improvement, but we make it specifically for the trigger.
Accessories and Attachments
If you are building a clone and are taking the time to research the gun itself, you probably don’t want to throw random crap on it. If you want to stay clone-appropriate (i.e. what was issued in the battlefield), there are specific options to choose from. Note that you don’t need all of these to have a clone-appropriate build. The core accessories for the Mk12 Mod 0 include:
- Sling (optional)
- Bipod (required)
- Scope (required)
- Scope Mount (required)
- Laser (optional)
*Â Discontinued items (scopes and laser) may be purchased used on auction sites.
** Leupold was the standard optic for the mk18 Mod 0. However, Leupold’s current Mark series offerings look nothing like the original. Night Force currently offers similar scopes to the original NF scope that was sometimes used. If you are interested in the same magnification, go with the NXS 2.5-10x42mm scope (but the objective is larger, so the profile won’t match). If you are concerned with the clone-consistent appearance of the scope, go with the NX8 1-8x24mm scope (though the magnification will not match).
***Â The appropriate scope ring height depends on the scope and other accessories (e.g. rail-mounted laser or rail-mounted night vision sight [AN/PVS-22]).
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