The 6mm Bench Rest Ackley (BRA)

This versatile setup of a Cadex Strike Nuke Evo and Atlas CAL Bipod, all topped with a Leupold Mark 5 HD 7-35x 56mm, perfectly complements a do-all cartridge like the 6mm BRA.

In the vast world of rifle cartridges, versatility is a prized trait. While usually something I consider when building a new rifle, the current shortages and often ridiculous prices being asked for components in the last few years had me considering factors that I had not before. I was in the market to build a new “plinking” rifle but given the current component climate and longer lead times for barrels, I wanted something that could serve more than one purpose. On top of versatility, I started heavily considering powder consumption, which I had not given much concern about in the past.

At the heart of this rifle is a Pristine 700-footprint action. This offering features an interchangeable six-lug floating bolt head, roller-cocking piece for super light bolt lift, double ejection pins, Sako-style extractor and much more.

My wife constantly shakes her head at me in confusion, but my constant pursuit of perfection and precision knows no bounds. This has become quite an issue for me, as a simple “plinking” rifle can’t just shoot “okay.” This plays a huge factor in my decision-making and led me down the rabbit hole of the 6mm cartridge world.

Not already owning a 6mm cartridge, I wanted to add a suitable steed to the stable. While there are many fantastic 6mm cartridges out there, a few key factors played into my decision-making process:

1. I wanted an inherently accurate cartridge.
2. I didn’t want it burning much more than 30 grains of powder.
3. I wanted something versatile so that if I wanted to, I could easily hunt varmints or medium-sized game.
4. I wanted the ability to use up to, and including, 105-grain class projectiles and be able to push them to at least 2,700 feet per second (fps).
5. I wanted it to be able to give me a competitive chance if I decided to shoot an F-Class or PRS-style match with it.

As many of you know, this quickly narrows down the search. While all great cartridges, the 6mm Dasher, 6x47mm Lapua, 6mm XC, 6mm BRX and 6mm GT use more powder than I wanted to consume for my new “plinking” rifle, and the 6mm PPC is not able to push the 105-grain class projectiles at the speed I was looking for. I quickly concluded that the 6mm Benchrest (BR) or 6mm Bench Rest Ackley Improved (BRA) would be the two options I would look at.

Aiding me in my decision, I know many folks with benchrest rifles, and they adore them. I didn’t know anyone when I was looking to build mine with a BRA, so I elected to be different and went the BRA route, and oh boy, am I glad I did.

Neil (Satch) Megyes, owner of Chinook Arms and Ibex Industries in Taber, Alberta, Canada, assembled this beautiful rig for me. He did a custom coating of his limited edition “Ibex Red” on the MDT ACC chassis, and I couldn’t be happier with how it turned out.

A close-up shot of another contender on the Remington 700 clone market with Pristine’s iteration of the Model 700 patterned action.

The 6mm BRA Cartridge Overview

The 6mm Bench Rest Ackley is essentially an “Ackley” version of the 6mm Benchrest cartridge. The BRA version offers enhanced performance by utilizing the “Ackley Improved” design philosophy. This design incorporated a steeper 40-degree shoulder angle, resulting in increased case capacity and improved performance compared to its parent cartridge with a 30-degree shoulder angle. Unlike the 6mm Dasher and 6mm BRX, also offspring of the 6mm BR case, the 6mm BRA’s shoulder location does not move. This allows the 6mm BRA to retain the full-length BR neck. This has the added perk of easier fireforming if you elect not to use commercially available 6mm BRA cases.

Versatility in Competition

The 6mm BRA’s origins lie in benchrest shooting, where precision and consistency are paramount. The cartridge’s exceptional accuracy, low recoil and flat trajectory make it an outstanding choice for various competitive shooting disciplines. In precision rifle matches, where shooters engage targets at varying distances, the 6mm BRA shines with its consistent ballistics, enabling shooters to maintain tight groups and hit targets at long ranges easily.

One of three final test targets shot. All groups are five shots grouped by projectile: (1) Hornady 108-grain ELD-Match, (2) Hornady 103-grain ELD-X, (3) Berger 105-grain Hybrid Target and (4) Hornady 87-grain V-MAX.

The low recoil of the 6mm BRA facilitates rapid follow-up shots, an advantage in timed and string-fire shooting competitions. Doubled with the cartridge’s inherent accuracy and long-range capabilities make it ideal for F-Class and Precision Rifle Series (PRS)-style competitions, where engaging distant targets with precision is the name of the game.

Since Vihtavuori N550’s velocity was the fastest of all powders tested, I explored it more with .2-grain charge weight increments. As you can see, all shot well.

I wanted to shoot projectiles on the heavier end of the 6mm family so distance and wind would not affect its flight as drastically at long range. My rationale would allow me to shoot F-Class with it if I chose to change things up from the main rig I use in that event, but also have something that I could go and bang steel with on the weekends. This led me to work with the Berger 105-grain Hybrid Target and the Hornady 108-grain ELD Match. Both shot well with powders like Hodgdon’s Varget, H-4350, CFE 223 and Vihtavuori’s N550.

I chose to go with a 1:7.5 twist Proof Research barrel, which allowed me to run 105-grain class projectiles with ease. After testing many different powder and projectile combinations, I concluded that I am quite the fan of the Berger 105-grain Hybrid Target being pushed by 31.3 grains of Vihtavuori’s N550. This combination was all set off by a CCI No. 450 Small Rifle Magnum primer and gave me, on my final day of testing, an average velocity of 2,840 fps, with a standard deviation (SD) of 6 fps and an extreme spread (ES) of 16 fps over a 20-round string.

Pictured: (1) Berger 105-grain Hybrid Target, (2) Hornady 87-grain V-MAX, (3) Hornady 103-grain ELD-X and (4) Hornady 108-grain ELD-Match.

The accuracy is what I find more impressive than the low SDs and incredible velocity out of such a small case. The first four, five-shot groups I shot out of this rifle were all using the Berger 105-grain Hybrid Target, but all were different charge weights of Vihtavuori N550. With some educated guessing, these loads were all assembled to determine what velocities I would see. The four groups together averaged .315 inch, with the best being .262 inch. If that isn’t a sign of good things to come, I am not sure what is.

I would explore other powders and projectiles, with the CCI No. 450 primer and Alpha Munitions case being constant. My overall goal was to develop multiple loads that would allow me to continue to shoot well with this rifle, even if I couldn’t find the components needed for my preferred loading.

The 6mm BRA cartridge utilizes spacers in a standard 308 Winchester AICS pattern magazine. These magazines from MDT ran flawlessly without ever failing to feed.

Varget is synonymous with competition and always seems to shoot well in everything I load it in, so there was no surprise when I got good groups and favorable SD and ES numbers in the loads I tested. However, it burns too fast for the BRA cartridge, and I could not load as high of charge weights before running into pressure issues with it compared to other powders. This resulted in decreased velocity with the heavier projectiles compared to some alternatives.

Hodgdon H-4350, another seemingly do-all powder at times, shot well and would be an excellent alternative to what I ultimately decided to run with as a final powder. It found favorable velocities consistently, with the speeds running faster than Varget and slightly slower than N550.

Much to my surprise, CFE 223 shot very well. It is not a powder I would typically think of to try in a cartridge such as the BRA. My good friend and shooting partner Charlie, and I couldn’t believe the performance we saw from this unsuspecting option. I laugh as I recall when we looked at each other in shock and chuckled at what was printed on the target downrange. The performance is comparable to what was seen with H-4350, but it did shoot tighter groups. I wouldn’t think twice about running this powder as an alternative.

A Redding Type S full-length bushing die set with micrometer bullet seating die and VLD profile seating stem was used to assemble all rounds tested.

N550 shot very well and is ultimately the powder I will primarily use for the 105-grain class projectiles. With a great case fill percentage and consistently higher velocity than the other powders tested, N550 is a clear choice if available.

Powders that I could not get my hands on but are at the top of my list of powders to test are Hodgdon’s H-4895, Vihtavuori’s N150, and Alliant’s Reloader TS 15.5. All these have been mentioned in the shooting community as ideal powders for this cartridge.

Varmint Hunting

The 6mm BRA offers the perfect balance of power and precision for varmint hunting. The cartridge’s high velocity and flat trajectory allow hunters to confidently engage varmints such as prairie dogs, groundhogs, and coyotes at extended ranges. The minimal recoil of the 6mm BRA enables hunters to maintain sight pictures and minimize disturbance to their shooting position, ensuring higher accuracy during follow-up shots if needed.

Additionally, the 6mm caliber is known for its excellent ballistic coefficients, which results in less wind drift, making it easier to compensate for those strong prairie crosswinds that can affect shots at extended ranges.

The second of three final test targets shot. All groups are five shots and loaded with Hodgdon’s CFE 223. Groups from top to bottom: Berger 105-grain Hybrid Target, Hornady 108-grain ELD-Match and Hornady 103-grain ELD-X.

This is the final test target featuring a five-shot group for the 87-grain V-MAX and CFE 223 combination.

While varmint hunting is something I have yet to dive deep into, I did want to develop a decent load if the opportunity for a dedicated varmint hunt ever presents itself. I chose the Hornady 87-grain V-MAX as a no-brainer projectile to fit this bill. I could utilize Varget and CFE 223 again for this projectile and I also tried Vihtavuori’s N140.

Varget shot the best group and had the best numbers by far, with a respectable average velocity of 2,969 fps. I believe this projectile warrants further testing, as the best group I shot so far with it is just over half-MOA. This is certainly usable, but I feel I did leave some performance on the table when prioritizing work on developing other loads.

Medium-Sized Game Hunting

Premium components from Alpha Munitions, CCI, Berger and Vihtavuori, assembled by premium Redding dies, make the brass to bang precision journey for the 6mm BRA an easy venture.

Though primarily designed for competition, the 6mm BRA rounds its quiver out nicely with the ability to harvest medium-sized game. When loaded with an appropriate hunting projectile like the Hornady 103-grain ELD-X, the cartridge can effectively take down game such as deer, antelope, and smaller predators. With performance similar to the long-prized 243 Winchester, don’t sleep on the 6mm BRA as a viable option when deer season comes around.

The 6mm BRA started on the benchrest circuit, where it excelled and found multiple podiums.

Hunters who prefer a flatter trajectory and less recoil will find the 6mm BRA an excellent choice, especially for midrange shots. It’s essential to ensure shot placement and select appropriate bullet designs to maximize effectiveness when hunting game with this cartridge. However, this can easily double as a hunting rifle when not being shot at a match.

One of the great attributes of the 103-grain ELD-X is you can easily use the seating depths, powders and similar charge weights as other projectiles in this weight class, such as the 108 ELD-Match. This adds to the ease of developing multiple loads for this versatile round.

Impressive results were had with all of the powders tested. CFE 223 had the best group shot during testing, but N550 remained supreme in the muzzle velocity column.

Ammunition Availability

While the 6mm BRA may not be as widespread as some more established cartridges, its popularity is steadily growing. Commercial loadings are not being offered yet, but handloaders have had their work cut down for them, with companies like Alpha Munitions now making 6mm BRA cases. However, the traditional option of fireforming 6mm BR cases from companies such as Lapua to the 6mm BRA chamber will always be there. If you cannot find stock on the Alpha 6mm BRA cases or decide to fireform your own, you still have a fantastic round in the 6mm BR that shoots very well from the BRA chamber. Don’t be scared to take advantage of this two-for-one scenario and shoot a match with full-power BR loads, all while fireforming your BRA cases.

Closing Thoughts

The 6mm BRA rifle cartridge has proven to be an incredibly versatile option for shooters and hunters alike. From precision competitions to varmint hunting and medium-sized game pursuits, this cartridge offers exceptional accuracy, low recoil and impressive ballistics, making it a top choice for those seeking a single cartridge to excel in multiple shooting disciplines. As the shooting community continues to recognize the benefits of this outstanding cartridge, the 6mm BRA is undoubtedly destined for even greater recognition and adoption in the years to come. While I have long known there is no “jack-of-all-trades” cartridge, the 6mm BRA sure comes close to checking all the boxes.

The 6mm BRA feels just as at home in a mountainous environment as it does wlooking out over a prairie field when hunting season is in full swing.