Rock Solid

Scott Lambin Carbines, Featured Articles, Rifles 0 Comments

Manufacturers of the demonized “black guns” have found themselves in a case of feast or famine since Killery’s tide took a turn prior to the election. Everyone thought she would win and we saw while Obama was in office…gun sales skyrocket. As we all know, politics play unfortunate roles in the trickle-down effect on the industry.

Rock River Arms was no different. They have always lead with quality, ingenuity and a what you see is what you get mentality. After a few months of building up a surplus, with anticipation of another Clinton regime; when President Trump won, they were left with a heap of inventory, and scratching their heads like many of us.

The small company out of Colona, Illinois got in line with many of the other AR makers in an effort to stand out, instead of remaining camouflaged in the noise. Our industry’s softening sales caused layoffs and a severe cut back on production, especially with black guns. Through all of it, Rock River Arms didn’t sit idle and wait for sales to pick up again…their skeleton crew saw the downtime as an opportunity to tend to smaller projects and break ground on an entirely new platform. This is where the BT – 3 [Billet 308] started.

The Redesign

The BT-3 is yet another black rifle that packs more of a punch than the infamous .223 of late. For Rock River Arms, it is a step towards the unknown [for the most part]. The precision CNC machine work to the matched receivers for starters is what gives the BT – 3 the flare and functionality that Rock River Arms has been in need of.  To the naked eye, some would consider the BT – 3 just another aesthetically pleasing AR10. Our experience suggests otherwise. Not only its cool-ness but our tested accuracy results and smooth function are what made our first impressions, lasting.

Angled and contoured mag well, and lightening grooves are just a couple added benefits to the new Billet design

The rifle is based on the “DPMS” style platform. We fed the platform with Magpul, Lancer, and standard issue GI magazines. From 10 rounds to 30 there wasn’t a feeding device that wouldn’t do its job while inserted in the gun. A major plus in my book; as the LAR-8 [X Series]will only accept FAL type mags due to when the system was designed and availability of that type of mag at the time.

The BT – 3 designs will also afford the “at home armorer” the convenience of continuity between small parts. When you have a platform that is as widely manufactured as the AR; pigeonholing customers to only buying proprietary parts quickly becomes a pain in the ass and much less appealing. We can attest to this during our testing process as the bolt catch on our test subject had a little too much Cerakote applied and did not operate as smoothly as we needed it to. A quick turn of a hex head wrench and an installation of a standard bolt catch was all it took to get the gun back in action.



Feature Rundown

The milled and matched receiver set is [for us] is most notable. I have always been preferential to milling versus forging in ARs. As we experienced, the milled receivers allowed us the ease of use to quickly swap out a bolt catch [3rdparty paint applicator] without a hammer, punch or vice, equating our time to money value…invaluable! This can be said for detent holes and other “dammit” pins that often find those working on forged rifles frustrated that a detent flew across the garage after removing a takedown pin or end-plate.

Not only does milling offer a maintenance benefit the cuts are applied to give your rifle a custom look that doesn’t compromise strength and offers a practical application use for grip, weight reduction, and balance. The BT – 3’s Contouring and angling of the magazine well allows for quick magazine changes while in a low-prone position where grabbing the magazine isn’t attainable from the bottom.


Rock Rivers newest competition trigger offers consistent and smooth breaks across many applications

Rock River designed and implemented a competition esq fire control group that has applicable uses not only on the PRS line, Static bench but can be easily implemented in the field for tactical application. To those who are familiar with past RRA triggers; this isn’t the National Match FCG that is found as an option with all other LAR rifles or Carbines. RRA’s competition trigger is a single stage with much, MUCH less creep than anything that has come out of the shop in Colona. Simply put, the new trigger is a single stage that offers more shoe surface to the finger of almost 80% [measured]. Its hammers reduced width allows for quicker response and increased “strikability”. Rock River tuned the accompanying springs for consistency and durability.

The BT – 3 features captured trigger and hammer springs to keep the rifle functioning, regardless of rates of fire, ammunition or transportation. Captured pins in many regards is an underappreciated feature. If you have ever had pins walk on you while getting after it…is sobering at best.  But, for every advantage comes disadvantage. The BT – 3’s anti-walk pins are calculated into the width of the receiver while in the mill. Swapping them out in the future will result in wasted time if the proper sizes are not taken into account.

Rock Rivers newest trigger is adequate for not only the slow, well aimed, and well-placed shooting cadences. It also proved effective for the targets that required more attention with Hornady’s 168 grain ELD or Gorillas 175 grain Sierra Match King projectiles. We measured the trigger out of the box and after 500 rounds (as usual). Before firing and after, the trigger broke at a consistent 4lbs with no added (felt) creep or over-travel. No matter your end use, the trigger is about as even as you can get [with a production rifle.]


The Magpul PRS stock served our needs most adequately throughout testing of the BT-3. The rifle is available with the 6 position collapsable Operator Stock.

Initially, we opted to test the rifle with Rock Rivers “Operator”- 6 position stock. For us, less stock noise and consistent “weld surface” suited our preference and needs for the perspective we were testing the BT – 3 in. We needed a permanent fixture to the rifle to seat high in the pocket of our shoulder for our use. Though the collapsible option is functional it was not what we needed. We took the rifle back to RRA to have the Magpul PRS stock installed.  In either case, ordering the BT – 3 from the factory, you have the option.


The standard 15-inch handguard is designed to dissipate heat while offering multiple points of rail attachments. Each handguard has a fixed 1913 Picatinny rail that extends the entire length for consistency in optics mounting. If we had our “way”, the BT – 3’s handguard would be of a lower profile to the barrel with an added couple inches in length. This is merely a personal and aesthetic preference; the original design of the handguard has served its purpose flawlessly.

At the end of its 20” chrome lined barrel, sits RRA’s operator muzzle brake. As designed, the muzzle device disperses energy efficiently with what we have coined the “face raker”; a series of serrations that provides a striking surface for impact needs. Whether you’re being defensive, offensive or tactical, the device serves its purpose well. We did not test the rakers capabilities during this review but plan to, in future articles.

As for the performance of the device design, the Operator muzzle device kept most of the energy away from the shooter during live-fire exercises. From future articles, we know that the engineers at RRA put more time that you would expect into the design process of each muzzle device. The angled horizontal and vertical cuts on the brake itself, paired with them .11” drilled holes around the muzzle disperse upwards of around 30% more energy than the A2 (birdcage) and close to 50% than that of a bulled barrel without a muzzle device.

Going Hot


The stainless bolt/carrier group in the BT-3 makes for consistent heat dissipation and close to effortless maintenance

Prior to any aftermarket mods, the BT – 3’s fit, fire, and function were not disappointing. The installation of the PRS stock reduced spring and buffer noise to almost non-existent. The stainless bolt and carrier chambered, fired and extracted our test ammo as designed, and offered a virtually wipe-off solution when firing suppressed [once the bolt became sluggish after 150 rounds]. After wiping the bolt and carrier with a dry cloth, we applied a liberal coat David Hogg’s tears then the BT – 3 was snappy and smooth again. [How they were obtained is classified].


The BT – 3 put up satisfying [and unexpected] accuracy results against our standard 100-yard process looking through a Nightforce 3.5-15×50 NXS series riflescope. The BT – 3 chewed through three types of ammo. Hornady’s 168gr ELD topped the bunch logging the best group of .53” unsuppressed between the 5 groups we averaged .69” from the prone, with bipods. Gorilla’s 175gr Sierra Match King loads weren’t too far behind the Extreme Low Drag – Match loads from Hornady. Our groups averaged 1.10” [to be expected with the BT – 3’s twist rate and heavier loads] while our tightest registered .83”. Honorable mention is in store for Hornady’s 155gr American Gunner loads. Though our results aren’t exactly “impressive” while shooting unsuppressed; our best group was still within the 1.5” threshold that RRA stands behind with their guns. [Stay tuned for suppressed results].

Hornady’s Extreme Low Drag – Match ammo proved to punch the tightest holes while shooting suppressed

Since jumping through the necessary hoops in Illinois to obtain and utilize silencers; we never leave home without at least one. We removed the Operator muzzle device and installed SilencerCo’s ASR muzzle device to accompany the Omega. We let the BT – 3 cool down to ambient the ambient temperature of 48 degrees, attached the silencer and began the same accuracy tests as we completed the hour prior.


The lightest load we tested resulted in the tightest groups. Hornady’s 155gr BTHP stacked themselves on top of each other after leaving SilencerCo’s Omega!










We couldn’t have recorded more lopsided numbers while silenced if we tried. To our surprise, Hornady’s more affordable 155gr BTHP, American Gunner topped the charts by stacking 3 rounds on top of each other measuring .332”. The average between all five groups with the more affordable ammo was .901”. The ELD and Sierra Match King ammo remained a tad over 1.5” averages.

A major point of contention while shooting suppressed [with many] is the POA/POI shift experienced, and in a tactical situation where cold bore shots are crucial to know and understand, this could be cause for even more concern. Our POA/POI shift was not unmanageable for our first outing. The 155gr BTHP suffered the least, impacting 1.93 inches low while Hornady’s 168’s measured 2.89” low and .11 inch left. Gorillas heavier loads found their targets somewhere in between at 2.21 inches directly below our point of aim.

Follow Through

With all the AR platforms on the market; moving forward, there will come a time where the hard lines between them are going to become nonexistent, let alone blurred…if they haven’t already. Every one of us on The BrassTacs team is students of the gun, one way or the other. Whether it be from precision, defensive or tactical perspectives the AR style of rifle is one of my personal favorites. Now instead of gathering many gassers for different uses, looking to one that fits the bill becomes more and more desirable.

The BT – 3 is moderately priced under $2500, which can be configured to fit most of your needs. If you were to special order your BT – 3 with an 18” barrel (for example), you have scratched the CQB or patrol itch while retaining the ability to stretch to 1000 or so with the right ammo and glass.

Regardless of your end user needs, the BT-3 is one of the .308 platforms that can fit in wherever you put it

Off the bench, the platform can be suppressed without too much of a difference in impact, so long as you know your equipment and can employ it properly. The rifle is adequately weighted and despite the solid piece of aluminum its receivers were cut from, it weighs .10 lb lighter than its LAR – 8 predecessors [with PRS stock installed].

With this rifle, we would venture to say that with a couple furniture modifications and a quick swap of glass, the BT – 3 could very well be used between a 3 gun match and PRS beginner competitions. Its versatility would also speak volumes in the Law Enforcement realms too…IF you’re willing to spend the money on one rifle – many use application, Rock River Arms new Billet 308 may be something to consider.


Rock River Arms BT – 3 Technical Specifications (Tested)

Type Semi-Automatic, Direct Impingement
Caliber 7.62x51mm/.308
Weight 10lbs [Unloaded]
Overall Length 42”
Stock MagPul PRS
Barrel 18” Chrome Moly 1/10 RH Twist
Muzzle Device RRA Operator [Brake]
Bolt/Carrier Stainless Steel
Receiver Billet Aluminum
Finish Tungsten Gray/Armor Black
Trigger RRA Competition
Trigger Pull 4lbs
Manufacturer Rock River Arms
MSRP $2200.00

About This Author

Scott Lambin

Scott is the founder of The BrassTacs digital publications. He is a veteran of the US Marines and has numerous deployments in support of the GWOT. Scott brings 17 years of experience to the publication. Focusing on practical application with all firearms. Scott focuses on hard end use, training and pistol and carbine perspective content.

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