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Exploring the SPR Rifle: The MK12 and Civilian AR-15 Clones

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When discussing long-range shooting, the AR-15 isn’t usually the first rifle that comes to mind for most. More often, enthusiasts consider bolt-action rifles or the larger AR-10 as the better choice. While both are top-tier choices, the AR-15 can be surprisingly effective at longer distances when it’s configured for that purpose. 

AR-15s are most commonly chambered in 5.56×45 NATO and have an effective range of around 500 yards in standard carbine configuration. However, with specific cartridge loads and a specialized upper receiver, a 5.56 NATO AR-15’s range can be extended to up to 700+ yards away. One such rifle, better known as the Special Purpose Rifle (SPR), is configured just for this purpose. 

SPRs are an incredibly popular choice amongst enthusiasts, as their long effective range and accuracy make them a more than a suitable choice for multiple applications like hunting, competitions, and recreational shooting. Today, we’re delving into the concept of the SPR Rifle, its history, and what separates it from a standard AR-15. 

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History of the SPR: The Mk 12 

The Mk 12, the first SPR model, initially began as an upper receiver upgrade for the M4. It was designed to serve in designated marksman roles, bridging the gap between standard-issue carbines and larger DMRs. Eventually, instead of an upper receiver, it was produced as its own rifle platform, which was type-classified as the Mk 12 Mod 0.  

Instead of the standard 14.5-inch barrel of the M4, the SPR utilized an 18-inch barreled upper that was optimized for use with a 5.56 NATO cartridge variant known as Mk 262. Mk 262 is a match-grade round that’s much better suited for long-range applications compared to the standard M855 green-tip cartridge. It used a 77-grain Sierra MatchKing bullet which was capable of accuracy up to 700+ yards away and became the standard ammunition for the platform. 

Over time, the Mk 12 Mod 0 design was slightly updated and reclassified as the Mk 12 Mod 1. The Mod 1 was similar to the Mod 0; however, it featured some slightly different components. Most notably, the Mod 1 came with a KAC free floating RAS handguard, whereas the Mod 0 used an A.R.M.S. Inc. Ex SWAN Sleeve mounted to a Precision Reflex Inc. Handguard. Also, the gas block was altered, and didn’t include a folding front sight post.   

Aside from this, both rifles came equipped with the same muzzle device, lower assembly, and came with either a fixed stock or an adjustable one. Also, there was one other variant of the Mk 12 known as the Mod H. Essentially, it was the same rifle as the Mk 12 Mod 1, but instead of an 18-inch barrel, it came with a 16-inch one. 

Each variant of the Mk 12 was incredibly versatile and was often kitted out with numerous accessories to make it more effective for long-range targets; it often was seen equipped with different optics, grips, and bipods

Despite being phased out of service in 2017, the Mk 12 SPR and its variants remain iconic pieces of firearm history. Today, they’re incredibly popular amongst clone builders and those interested in long-range 5.56 builds. 

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Civilian SPR Platforms 

SPR style AR-15s have risen in popularity since their inception, showcasing the versatility of the AR platform. While the original Mk 12 SPR is an iconic rifle, it lacks many of the modern comforts you’re likely accustomed to. The handguard, for example, is quite heavy and bulky compared to the slimmer and lighter M-LOK handguards seen on most ARs today.  

At their core, an SPR is simply an 18-inch (sometimes 16-inch) AR-15, that’s tailored for long-range engagements. As we mentioned before, these AR variants lend themselves greatly to recreation, competition, and hunting. As such, there are a lot of manufacturers producing the components necessary for modern SPR builds, as well as many brands with their own lines of SPR-style rifles.  

SPR-Configured AR-15s 

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BCM: Bravo Company Manufacturing is a premium brand that’s well-regarded for their high-quality rifles and other AR components. In their wide array of specialized rifle setups, their RECCE 18 series AR-15s are some of the most popular for enthusiast SPR setups.  

The RECCE 18 comes in two distinct variants, the KMR-A Precision and the MCMR Precision. Both rifles are practically identical, with the key difference being the type of handguard they use. As their name suggests, the KMR-A uses a KMR-A KeyMod handguard, while the MCMR variant comes with an MCMR M-LOK handguard. Aside from this, both rifles come with an 18-inch stainless steel barrel with a 1/8 twist rate, a rifle length DI gas system, BCM furniture, and a BCM compensator. Additionally, both rifles come equipped with an upgraded BCM charging handle, their PNT trigger, and other lower components. 

Both rifles have a low weight of only 7 pounds, allowing you to still have a lightweight rifle setup, even when accessorized. BCM, known for their high degree of quality, thoroughly tests their rifles before sending them out. So, regardless of which one you choose, you can rest assured knowing your rifle will be more than capable of making precise shots on targets at great distances.  

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Cobalt Kinetics: Cobalt Kinetics is a premier manufacturer of high-quality AR-15s, and one of their popular lines of rifles is their SPR Series. Their SPR Series rifles have varying barrel lengths, can be chambered in a multitude of calibers, and come pre-equipped with enhanced controls from the factory. 

There is an incredible degree of adaptability found in these rifles. Depending on the model you look at, they can be chambered in .223 Wylde, 6.5 Grendel, or 6mm ARC. Each one is highly conducive to long-range precision, with 6.5 Grendel and 6mm ARC both having effective ranges of 800 to 1000+ yards. .223 Wylde, in contrast, is a hybrid chambering that allows you to use both .223 REM and 5.56 NATO cartridges without negatively affecting the ballistic performance of either. Additionally, they all come standard with upgraded Geissele triggers, Radian Raptor charging handles, B5 Systems furniture, ambidextrous controls, and a VLTOR 5-position buffer tube.  

Aside from an optic, these rifles are ready to provide you with incredible performance out of the box. Regardless of whether you’re wanting a modern take on the 5.56 NATO SPR or if you’re looking for a more optimized long-range caliber like 6mm ARC or 6.5 Grendel, each one is capable of landing shots on targets up to 700+ yards away. 

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Daniel Defense: Practically needing no introduction, Daniel Defense is one of the most popular rifle manufacturers around. As such, it shouldn’t be a shock to learn that they also produce an excellent SPR option, the Daniel Defense MK12.  

Daniel Defense’s MK12 rifle is essentially a modern take on the original Mk 12 SPR design, albeit with a few upgrades. It comes standard with an 18-inch cold hammer forged barrel, a 12-inch free floating quad rail, enhanced mil-spec controls, and DD’s upgraded stock and grip. Instead of a mil-spec trigger, this rifle comes equipped with a Geissele SSA trigger, making the MK12 an excellent rifle for precision shooting.  

Paired with a solid optic, the MK12 from Daniel Defense is a solid choice for an SPR. While it doesn’t offer ambidextrous controls, the prominent level of quality in the parts that make up the rifle, as well as its accuracy, makes the MK12 great for any application that requires long-range precision.  

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Custom Builds 

The beauty of using the AR-15 as a rifle platform is that the customizability makes basically any build possible. Building an SPR can easily be done, and doing so gives you the ability to control the parts that go into your build.  

Each of the models that we mentioned previously hovers around the $1,800 to $2,500 mark, and assuming you’re keeping this same budget, the possibilities for your build are endless. Many premium AR parts manufacturers offer high-quality components that are perfect for SPR builds. For instance, you could use a fully ambidextrous lower receiver like those from American Defense or opt for an enhanced trigger package over a standard one when building your rifle. 

Still, building an SPR Rifle is more than possible when on a budget. The sheer number of manufacturers producing parts for AR-15s makes it incredibly easy to look for deals on quality rifle parts. This same notion applies to rifle accessories as well. Take optics, for instance. They are one of the most expensive additions you can make to a rifle, but nowadays, it’s common to find high-quality optics at lower prices.  

Optic brands like Primary Arms Optics have excellent choices for all SPR variants. There’s a lot to consider when choosing a scope for a long-range rifle build, so much so that it can be confusing when you’re new to these platforms. Fortunately, our long-range scopes buyers guide will round out your knowledge of what to look for in an optic, as well as some great options to start with.  

Though the idea of building being less costly compared to buying a rifle isn’t always the case, it’s worth considering if you want a new rifle fitting your personal standards. We even have an article highlighting an AR-15 SPR build that focuses on creating a modern version of the Mk 12.  

Clone Correct SPR Builds 

When it comes to building a ‘clone-correct’ rifle, it isn’t always easy to do since they often take specialized components to achieve a certain look. While this is true of most clone builds, it’s quite easy to build an SPR clone.  

Many of the components needed to build a clone-correct SPR can be found in our online store, as they used mostly mil-spec components for the lower. As we mentioned before, the upper receiver was the most unique part of the rifle, compared to a standard carbine that is. Fortunately, Precision Reflex Inc., the manufacturer who made the original handguard for the Mk 12, not only continues to make these handguards, but they also produce complete upper receivers for SPR builds.  

They have uppers available in each of the main Mk 12 configurations, as well as additional ones if you aren’t trying to build a clone correct rifle. Once paired with a mil-spec lower and the furniture option of your choice, all you need to do is pair it with the accessories and optics you prefer, and your build is complete. 

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The Mk 12 SPR effectively bridged the gap between the standard issue carbines and larger DMR platforms, adding a new degree of precision and versatility to the AR-15 platform. The lightweight, modularity, and long-range capabilities of an SPR setup make it an incredibly utilitarian tool that’s worth adding to your collection.  

SPR Rifle setups like this show exactly how adaptable the AR-15 is. Whether you choose to build your own or opt for a factory-made rifle, the familiarity and customizability of an AR-15 in an SPR configuration is perfect for everything from recreation to hunting and competition. Once your rifle’s built, we recommend kitting out your rifle with high-quality accessories to enhance your experience.  

Our blog has many articles focusing on key upgrades for your rifle. One such upgrade that’s key for SPR setups is the bipod. Check out our beginner’s guide to bipods to see what all is available for your rifle and continue to follow our page to see everything else that’s coming.