LaRue Tactical's Optimized Battle Rifle (OBR)
by Cameron Hopkins

Robert Heinlein was speaking of human beings at the time, but he could have just as easily been referring to rifles when he said, “Specialization is for insects.” The philosopher-writer who authored Stanger In A Strange Land argued that a man should be versatile, able to “...change a diaper, plan an invasion, butcher a hog, conn a ship, design a building, write a sonnet, balance accounts, build a wall, set a bone, comfort the dying, take orders, give orders, cooperate, act alone, solve equations, analyze a new problem, pitch manure, program a computer, cook a tasty meal, fight efficiently, die gallantly.”

Which, if we were to crawl into Mark LaRue’s head, is the same principle behind LaRue Tactical’s Optimized Battle Rifle (OBR): a general-purpose 7.62x51mm NATO semiautomatic weapon system designed to tackle a panoply of tasks. The OBR is capable of everything from building-clearing to 1,000 yard first-shot hits.

The idea of a semiautomatic .308 Win. capable of sub-MOA accuracy, yet retaining FAL-like reliability, has been gaining momentum since the Navy SEALs first adopted the Mk 11 Mod 0 in 1990.

More recently, in 2005 the U.S. Army issued a solicitation for what would become the M110 SASS (Semi-Automatic Sniper System). Knight’s Armament Co., maker of the Mk 11 Mod 0, won the contract with a rifle similar to, but enhanced beyond, its Mk 11 Mod.

La Rue’s OBR is cut from the same cloth as the SASS and the Mk 11 Mod 0, namely that of Eugene Stoner’s AR-10, the original ArmaLite rifle chambered in 7.62x51mm. It was here in the AR-10 that Stoner integrated his signature trademarks of direct gas impingement operation and a rotary bolt with helical locking lugs. However, a lot of improvements have obviously come in the ensuing half-century of building Stoner-based weapon systems, including when he tweaked his original design while working with Reed Knight, Jr. on the Mk 18 Mod 0.

LaRue’s OBR is a variation on the Stoner theme - and one that has indeed “optimized” everything about the weapon system. It’s important to understand that the OBR is a fresh take on the AR platform, the major components machined in-house on CNCs from billet 7-series aluminum. This is not a bunch of out-sourced parts mix-and-matched to make a gun. (Which is not to imply otherwise for Knight’s M110, which is also manufactured in-house at Knight’s state-of-the-art facility, but a lot of today’s AR-based brands rely on vendor-supplied components.)

Optimized Features

So what exactly is optimized in the Optimized Battle Rifle? It’s impossible to be specific without a set of gauges and micrometers because LaRue isn’t divulging any trade secrets. But an educated guess is that the upper receiver is designed to increase performance, strength and rigidity with dimensions and tolerances that aren’t generally found on other AR-based .308 receivers.

The LaRue upper is CNC machined from 7075-T6 aluminum alloy - true aerospace-grade material - and features an interface at the front (where a delta ring would go) with four bolts to attach a free-floating handguard. This is the most obvious difference in LaRue’s proprietary upper receiver configuration from a Stoner “barrel nut and delta ring” setup. LaRue is no dummy. His receiver neatly side-steps the myriad patents and patents pending on the many free-float forend systems for a conventional receiver.

On top of the receiver sits a monolithic, one-piece Mil-Std M1913 rail with a 20 MOA slant. The cant is designed to allow night vision devices, such as an AN/PVS-22, to be positioned in front of a day optic with correct alignment. It also helps for zeroing a scope at 1,000 yards.

The barrel extension incorporates specially designed feedramps cut for the geometry of the 7.62 cartridge. The bolt cam slot is machined precisely for LaRue’s proprietary bolt carrier group, which features a hard-chrome finish. That’s about all the specifics one can arm-twist out of LaRue on the upper receiver.

Down below, the lower is also CNC machined right there in the “dead center of Texas” at LaRue’s facility in Leander. Perhaps the scenic Hill Country inspires LaRue; indeed, the machine work on the OBR is a thing of beauty. The lower receiver is conventional, other than accommodating an M110 magazine. The gun comes with two LaRue steel magazines, however, the first thing a purchaser does is load up on Magpul 20LR PMAGs, which work flawlessly in the OBR. Otherwise, the lower receiver follows the Stoner pattern though the trigger guard is slightly elongated and oval shaped. The controls - mag release, selector and bolt-catch - are all standard. LaRue’s logo of a silhouette of the State of Texas with LaRue Tactical inscribed is machined into the right side on the mag well.

Eighteen-inches is Mark LaRue’s personal recommendation for an OBR, but the rifle is offered in 16.1 and 20 inch lengths. The rate of twist is 11.25:1 right-hand. The barrel is made from what is coyly described as LW50 stainless without any further elaboration, in keeping with LaRue’s penchant for maintaining proprietary trade information. However, a quick Google of LW50 reveals, “Lothar Walther GmbH is a German rifle barrel maker who claims a proprietary barrel steel LW-50, or LW 50, or Lothar Walther 50, is a significant improvement over 416R/416BQ stainless rifle steels. The superiority pertains to corrosion resistance and accurate barrel life.”

LaRue guarantees sub-MOA accuracy and a survey of the Internet’s most widely trafficked AR-oriented websites reveals that’s indeed valid. One happy OBR owner posted a photo of a 6-inch group on a steel plate at 1,000 meters, a full kilometer! No one rifle is indicative of an entire manufacturer’s production, but the norm on the ‘Net seemed to be in the 0.5 MOA to 0.75 MOA range and a single complainer alleging poor accuracy could not be found.

In this writers opinion, the single most important component on any rifle, the trigger, is most assuredly optimized. LaRue’s OBR comes with a Geissele SSA two-stage combat trigger, which typically breaks at 5 lbs. after a nice bit of free travel in the first stage, allowing you to prep the trigger. The pistol grip is a Magpul MOE (without a finger bump, thankfully) in a color that is proprietary, called LaRue UDE. (I’m guessing here: Urban Dark Earth?)

Choosing Magpul furniture as a means of optimization is smart. The cleverness extends to the buttstock which is a modified (“optimized”) version of Magpul’s CTR carbine stock, also in LaRue UDE color. But the ingenious part is a self-retracting cheekpiece that raises the shooter’s head to align with a magnified optic yet when the charging handle is pulled back, the cheekpiece self-retracts to allow the handle to move.

The charging handle is a PRI Gas Buster with its patented “gas seal” design that channels blow-back gases, oil, and crud away from the shooter’s face. This is not an issue unless the weapon is suppressed, but then it’s a major annoyance. The OBR is designed to accommodate a suppressor. The gas system features a two-position switch for a large or small port for unsuppressed or suppressed fire. An optional SureFire muzzle brake and suppressor adapter can be ordered with your OBR.

Rounding out the optimization package is a set of Troy Industries BUIS with the LaRue logo. Everyone has an opinion on BUIS ranging from “totally unnecessary” to “absolutely vital” and I won’t enter that fray, but I will say that if you’re going to run with BUIS, it’s hard to beat Troy’s product for sheer sleekness of design and ruggedness of build.

Accessory Friendly

LaRue’s forend is what might be termed an SPR style, round and smooth with holes drilled and tapped to accept short sections of Mil-Std M1913 rail. You can position the rail sections as you choose at 3, 9 or 6 o’clock. On a general-purpose rifle like the OBR, the 6 o’clock position is typically used to mount a Harris bipod (available from LaRue with an enlarged locking lever) or a vertical grip. I used the position for a LaRue-improved Harris bipod as the OBR at 9 lbs. unloaded is too heavy to hold with a vertical grip. Add an optic, and the bipod makes even more sense.

The 3 and 9 o’clock positions are ideal for electronic accessories such as a SureFire RAID WeaponLight, an Insight ATPIAL IR/Vis targeting illuminator or other laser-light setup. Though some may prefer to run the ATPIAL on the 12 o’clock rail; favoring to deal with a parallel zero with a slight vertical dispersion rather than a horizontal.

LaRue’s monolithic 12 o’clock rail provides ample real estate to mount magnified and non-magnified optics as well as your choice of night enhancement devices, either thermal or I2. An Oasys thermal imager mounted in front of a Schmidt & Bender 1.1-6x day optic rendered stunning performance. Footsteps on the floor where a person had just walked could be seen. Thermal imaging has its drawbacks (can’t see through glass, for instance) but it’s five kinds of cool to look through.

For low light applications, a Universal Night Sight (UNS) AN/PVS-22 from Knight’s Armament Co. is an excellent choice. This NOD is ideal for a general purpose rifle, not too big like a MUNS and not too small like a CQB sized unit. I can discern and identify a man-target to 200 meters; the MUNS is good to 400 and the CQB maybe to 100 on a moonlit night.

For day optics, the world is your oyster. Bearing in mind Heinlein’s dictum about versatility and specialization, I shed away from purpose-built optics for the OBR which range from a non-magnified Aimpoint to a high-magnification tactical scope, like a US Optics 6-17x. I opted for the aforementioned S&B 1.1-6x with an illuminated German post reticle. I can use the duplex-style stadia as a hold-over indicator, which is sufficient with a 200 yard zero and .308 Win. ammunition with a high BC bullet like a 168 gr. HPBT.

Accessorizing the OBR brings out the rifle’s wide spectrum of potential. Yes, it can be configured as a mission-specific, melon-popper for booger-eaters in the mountains of Afghanistan or it can be suppressed to hunt hogs in Texas or kitted up for maritime interdiction or swung to and fro in room clearings, but really the OBR is a generalized weapon system. It can do whatever you want with the right accessories.

Since Heinlein had the first word in this story, he deserves the last. It has nothing to do with the OBR, but it’s a gem and certainly his most famous aphorism: “An armed society is a polite society.”

This article first appeared in Small Arms Review V15N3 (December 2011)
and was posted online on November 1, 2011


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