Rock River Arms LAR-300 X-1 Review


Rock River Arms LAR-300 X-1

We get the party started with the Rock River X-1 in .300 BLK.

Building off the success of previous models, the LAR-300 X-1 brings a whole lot of features to the .300 BLK party. Photo by Jeff Jones
Building off the success of previous models, the LAR-300 X-1 brings a whole lot of features to the .300 BLK party. Photo by Jeff Jones

While the .300 AAC Blackout has continued to grow in popularity among shooters, the new LAR-300 X-1 rifle from Rock River Arms takes the cartridge to a whole new level of performance. As an amalgamation of former models and concepts, including the Fred Eichler Series LAR-15, the X-1 brings together the best features from Rock River’s past and yet is a beast of its own kind. The X-1 has existed in 5.56 NATO for a few years now, but the jump into the .300 BLK chambering figures to be another huge leap forward for the X Series of rifles.

What makes the LAR-300 X-1 stand out is the 18-inch fluted and bead blasted, stainless steel, cryo treated barrel and the Rock River Operator A2 buttstock and TRO-XL handguard, which come in either tan or black finishes. The tan-finished rifle comes standard with a fixed buttstock and is ideally suited for hunting, while the black rifle comes with the adjustable CAR buttstock, though both rifles can be purchased with either option.

Not only does it look slick, the fluted, stainless steel barrel is durable and highly accurate, producing groups in our 100-yard testing that are very respectable for the cartridge—Nosler’s Match Grade 125-grain load produced a best group of .81 inches, while Hornady’s 110-grain V-MAX constricted to .59 inches. The LAR-300 X-1 comes with either the Hunter muzzle break (tan model) or the Beast (black), both of which feature a 5/8-24 threading.

Rock River’s two-stage trigger, which is among the best as far as AR-type triggers go, also improves accuracy. The break is crisp and the reset audible. The trigger guard is extended to make room for gloved hands and winter shooting conditions—a particularly nice touch for those predator hunters among us.

The LAR-300 X1 comes with one of two Rock River muzzle brakes: the Hunter (shown here) or the Beast, which comes standard on the black rifle. Photo by Jeff Jones
The LAR-300 X1 comes with one of two Rock River muzzle brakes: the Hunter (shown here) or the Beast, which comes standard on the black rifle. Photo by Jeff Jones

The TRO-XL handguard is ergonomically designed to fit the contour of your hand or shooting sticks and features a single, full-length Picatinny rail at the 12 o’clock position. Cutouts in the handguard help reduce weight without giving you the jagged feel of a quadrail. The rail continues along the upper receiver, making plenty of room for a massive—and massively impressive—optic like Steiner’s M5Xi in 5-25x56mm, which is mostly overkill for the .300 BLK but provides maximum accuracy nonetheless.

For the review, the M5Xi was secured with Burris’ P.E.P.R. mount, which attaches or detaches easily and quickly. With German glass, reticle illumination and true 25x magnification, the M5Xi is as durable and optically crisp as they come. Most of the shooting done for review was conducted with an EOTech HHS II with G33.STS magnifier, which is an ideal pair for close quarters work, be it coyote, hog, steel targets or paper silhouettes.

The LAR-300 X-1 comes with forged upper and lower receivers and an “X Series” emblem on the ejection side of the lower receiver. The upper receiver comes with a forward assist and Rock River Star safety, as well as a Hogue rubberized pistol grip. The rifle is relatively heavy for an AR-15-type platform, weighing in at 8 pounds, but the additional weight also helps stabilize the shot—ideal for predator hunting and overall accuracy.

All Blacked Out

Rock River Arms LAR-300 X-1The LAR-300 is chambered in .300 BLK, which was developed originally by J.D. Jones as the .300 Whisper and standardized by Advanced Armament Corporation (AAC) in 2009. The cartridge has the capacity to produce smaller bullets at supersonic velocities or heavier bullets at subsonic velocities. Subsonic velocities usually hover near 1,000 fps, while supersonic loads usually come out at about 2,100 to 2,300 fps and produce generally better accuracy out to 100 yards.

The great upside of the .300 BLK, however, is the ability to suppress the rifle and send out lethal .30-caliber bullets at close distances, either for military-type applications or close-range hunting—hogs, deer and so on. Folks often complain about the lack of performance at ranges greater than 100 yards, but the reality is that the .300 BLK is purpose-built for close quarters work. In that capacity, it does very well.

Paired with a suppressor like SilencerCo’s new titanium Omega, the .300 BLK is devastating on close-range critters, whether you’re trying to eradicate hogs, take out a pesky coyote or cull deer in South Texas. Short, light and quiet, SilencerCo’s Omega is designed with a Specwar ASR muzzle brake and anchor brake to help reduce recoil. Not only is the Omega great for the .300 BLK, making in- or -over-the-ear hearing protection unnecessary, it fits any caliber from 5.7mm to .300 Win. Mag.

On a recent cull deer hunt in South Texas at Mellon Creek Outfitters near Refugio, Texas, the combo of Omega and .300 BLK were extremely efficient at close-range culling. Rather than scattering after a shot, most of the deer and hogs stay put, allowing for additional follow up shots. Firing shots from a truck—without additional hearing protection—was routine and pain free. Similarly, the LAR-300 X-1 would do well pulling double duty as a home defense gun; paired with a can, it’s extremely easy on the ears in confined quarters that would otherwise leave the ears ringing for days.


Rock River Arms LAR-300 X-1In the accuracy department, the X-1 performed well, especially for caliber. The .300 BLK isn’t typically the most accurate cartridge at 100 yards, but both Nosler and Hornady loads (both supersonic) produced best groups well under an inch. Subsonic loads are less accurate at 100 yards, but still under 2 inches and more than suitable for hunting or self defense purposes—especially considering the cartridge was designed more for the 0-50 yard range, or closer.

While in the past there haven’t been great options for the .300 BLK, there are now more quality loads than ever. Nosler’s Match Grade loads, as well as Hornady’s 110-grain V-MAX, were among those that performed best in our testing. Beyond that, Noveske, SilencerCo and SIG—to name a few—all produce quality loadings for the cartridge.

Parting Shots

The .300 BLK is as popular as ever, and the LAR-300 X-1 is as fine a rifle as you’ll find in that chambering. Rock River’s AR builds are superb, and they come in at a price that’s quite reasonable (starting at $1,585). The rifle comes fully loaded with a Rock River two-stage trigger that’s at the top of its game. Suppressor-ready with a great barrel, the LAR-300 X-1 is tough to beat. It’s not a 200-yard, big game gun, but then it was never designed to be. Within the limits of its intended purpose, the X-1 chambered in .300 BLK is extremely proficient.

The .300 BLK isn’t known for its accuracy at 100 yards, but the LAR-300 X-1 performed beyond expectations. Photo by Jeff Jones
The .300 BLK isn’t known for its accuracy at 100 yards, but the LAR-300 X-1 performed beyond expectations. Photo by Jeff Jones

Manufacturer    Rock River Arms
Type    Direct-impingement, semi-automatic
Caliber    .300 BLK
Barrel    18-inch fluted, bead blasted,
stainless steel, cryo treated
Handguard    RRA TRO-XL extended length, free float
Stock    RRA Operator A2 fixed
or RRA Operator CAR adjustable
Grip    Hogue rubberized grip
Trigger    RRA two-stage
Overall Length    38.5” (A2 stock)/36.5 (CAR stock)
Weight    7.9 pounds
MSRP    $1,585

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  1. I don’t see the point. It’s not a particularly powerful load at supersonic speeds (in fact, its underpowered compared to a standard 5.56mm) and at subsonic speeds its essentially no better than a .45ACP +P loading. If I need to do relatively close work with a suppressor I’d rather not lug around a rifle when a pistol will do.


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