6mm ARC Varmint Loads in HOWA's Mini Action Rifle

The 6mm ARC was introduced by Hornady in 2020 and given the Sporting Arms and Ammunition Manufacturers’ Institute (SAAMI) stamp of approval shortly after. The initial goal included developing a round that would function in the AR-15 platform while dramatically improving on 223 Remington/5.56 NATO performance. This is a common theme that has resulted in several popular cartridges, yet each has met individual limitations.

The 6mm ARC (Advanced Rifle Cartridge) was purpose built to handle long-for-caliber 105- to 110-grain bullets with high-ballistic coefficients (BC). The original focus of creating an AR

round meant introductory load data was tailored for “gas guns,” with pressures held to 52,000 pounds per square inch (psi), like the 223 Remington and 5.56 NATO. “Bolt gun” load data came along a little later, running pressures up to 62,000 psi. ARC rifles were given 1:8 to 1:7.5 twist barrels to stabilize high-BC bullets reliably.

ARC cases were formed from 6.5 Grendel brass, the shoulder/neck pushed back to accommodate longer bullets without intruding into powder space and while also accommodating standard AR-15 magazines. Properly headstamped small rifle primer cases are available from makers, such as Hornady and Starline. The 6mm ARC, on average, burns just 25 to 30 grains of powder and hits 2,750 to 2,850 feet per second (fps) with 105- to 110-grain bullets from a 24-inch barrel - the round generally gaining/losing 30 fps per inch of barrel added/subtracted.

More recently, the 6mm ARC became popular with precision rifle shooters because of its inherent efficiency, mild temperament and long barrel life. It also makes a fantastic hunting round for big game up to deer and wild hogs. I used the 6mm ARC in its infancy, to shoot a mature Texas whitetail at 268 laser-measured yards - a buck that minced just 10 yards before tipping over. I’ve also bagged more than a dozen wild hogs with the ARC, all while shooting Hornady’s 103-grain ELD-X bullet.

The 6mm ARC’s ballistic talents and powder capacity make it an obvious varmint-shooting contender. When I discovered HOWA’s carbon-barreled Mini Action rifles at SHOT Show 2023, I knew I’d found an ideal vehicle. Unable to decide which rifle I liked best; I ordered one each of HOWA’s Carbon Elevate and H-S Precision Carbon Fiber models. These rifles are essentially the same, the former bedded in a Stocky’s Carbon Composite AccuBlock stock with a LimbSaver recoil pad, and the latter an H-S Precision carbon-fiber creation. Both are, of course, based on HOWA’s trim Mini Action. They hold 20-inch carbon-wrapped barrels with 5⁄8x24 muzzle threads that make them suppressor ready, a user-adjustable H.A.C.T. 2-stage trigger and detachable polymer magazine. Both carry sub-MOA guarantees.

These are trim, lightweight rifles ideal for a full day of aggressive coyote calling or the type of walkabout varmint shooting we do so much of up here in northern Idaho’s logging clear-cuts.

Each rifle received an identical Bushnell Engage 6-24x 50mm scope set in matching Vortex 30mm rings on EGW Mini Action Picatinny rails. The Carbon Elevate has a 0-MOA rail, the H-S Precision has a 20-MOA rail. The differences were based on my plans to shoot light, moderate-range bullets from the Elevate and heavier, long-range bullets from the H-S Precision, justified by the slightly heavier mass of the H-S Precision rifle.

Bushnell’s Engage series are budget-friendly optics including both exposed turrets and a ballistic reticle ideal for dynamic varmint shooting. The 6-24x 50mm configuration seemed well suited to the 6mm ARC’s capabilities, whether shooting across a grown-over stump field in northern Idaho or stretching range in the open, wind-swept prairies of Wyoming. The finished weight with mounted optics was 7.17 pounds for the Elevate and 7.39 pounds for the H-S Precision. The Carbon Elevate’s trigger broke at 2.82 pounds and the H-S Precision at 3.15 pounds.

Carbon Elevate loads were assembled using lightweight varmint bullets for moderate-range ground squirrels or coyote calling. These included Sierra’s 55-grain BlitzKing (.225 G1 BC at 2,950 fps), Barnes 62-grain Varmint Grenade (.199 G1 BC), Hornady’s 75-grain V-MAX (.330 G1 BC) and Berger’s 80-grain Flat Base Varmint (.300 G1 BC). The Sierra is simply the lightest 6mm/.243-caliber bullet available, so it seemed important to see how the longer jump into the lands and fast rifling twist would affect accuracy. The Varmint Grenade was a natural choice, as the lead-free composition makes it relatively long for weight and is legal in places like California with lead-bullet bans. Hornady’s 75-grain poly-tipped/boattail V-MAX was a shoo-in, and Berger’s 80-grain Flat Base Varmint offers some of the most consistent accuracy in my experience and an impressive BC.

For the H-S Precision Carbon Fiber I chose heavier bullets, seeking long-range options for a windy-day prairie dog shooting or heftier rockchucks. These included Berger’s 88-grain High BC Flat Base Varmint, Sierra’s 95-grain Tipped MatchKing, Speer’s 100-grain BTSP and Berger’s 105-grain VLD Target. The High BC Flat Base Varmint provides explosive terminal performance and improved wind-bucking characteristics via a .380 G1 BC. Sierra’s 95-grain MatchKing provides an exceptional .500 G1 BC (at 3,050 fps) and “controlled-expansion” qualities on larger varmints such as coyotes. Speer’s 100-grain BTSP is thin jacket, enough it typically flies apart from fast-twist barrels at 6mm Creedmoor velocities, making it an affordable varmint-sniping option for the 6mm ARC. Its purported .446 G1 BC makes it a great long-range choice. Finally, I included the 105 Berger VLD Target, with its fantastic .517 G1 BC, as it is a consistent performer in terms of accuracy and aggressive expansion on varmints.

I have a great deal of experience with the 6mm ARC at this point. This allowed me to make some pretty solid choices regarding compatible powders that provide excellent combinations of velocity and accuracy, particularly with heavier bullets. I also added a few newer powder options that show promise in this round.     

With lighter bullets, Accurate 2200 sat at the fast end (No. 72 on the relative burn rate), with Alliant Power Pro Varmint (No. 93) occupying the slow end. With the heavier bullets, slower-burning powders sitting between Accurate 2460 (No. 89) to Hodgdon 4350 (No. 124) were auditioned. The outliers include A-2200 at the fast side by a wide margin and Accurate 2700 and Hodgdon 4350 at the slow end by a wide margin. Most 6mm ARC-compatible powders sit between Vihtavuori N-133 (No. 84) and IMR-8208 XBR (No. 90) for lighter bullets, and Accurate 2520 (No. 104) and Hodgdon LEVERevolution (No. 113) for heavier bullets. Past results have shown Alliant Power Pro Varmint, Hodgdon CFE 223, Alliant Power Pro 2000-MR and Hodgdon LEVERevolution – No. 93, 111, 112 and 113 on the relative burn chart, respectively – to be top choices for typical heavy-bullet loads, providing top velocities and consistent accuracy. You could choose only these four powders and do quite well with the 6mm ARC.

Of the many options available, Benchmark (No. 85) just had to be auditioned, as well as Ramshot X-Terminator/Accurate 2230 (No. 87 and 88, and essentially the same powders), Hodgdon 335, Alliant Reloder 15.5 TS, Ramshot TAC and Winchester StaBALL Match. I find Reloder 15.5 TS and StaBALL Match the most intriguing, as they are super clean and temperature stable and have provided excellent accuracy combined with very low extreme velocity spreads in the many cartridges I’ve tried them in so far.

Federal Premium Gold Medal Match Small Rifle primers - GM205M - were chosen for ignition. Starline’s recently released 6mm ARC brass was used throughout and, as usual, was exemplary in every aspect. Each powder charge was weighed on an RCBS beam scale, and Hornady Custom Grade Dies and an Area 419 ZERO Reloading Press were used to assemble all loads. Shooting was conducted from a bench in fairly breezy conditions, which I blame some of the fliers that ruined otherwise tight groups. None of the listed loads showed any signs of excessive pressure.

Considering the long jump into the lands required of the 55-grain bullet, it provided some worthwhile groups, as well as screaming velocity. Of the powders tried, IMR-8082 XBR proved the least appealing for this bullet/cartridge. Velocity topped out at just 3,151 fps and all loads broke outside of an inch. Accurate 2200 provided one sub-1-MOA group, using 29 grains of powder and sent at 3,200 fps. The clear winner was Alliant Power Pro Varmint, with all groups printing into less than ¾-inch and hitting 3,391 fps with the 33.5-grain maximum load.

Experience has shown that individual rifles either love or hate Barnes’ Varmint Grenades. The HOWA Elevate struggled a bit with the 62-grain 6mm version. Ramshot X-Terminator did the poorest, grouping into about an inch at 3,372 fps using the maximum/compressed load of 32.5 grains of powder, but also producing one of the worst groups of the entire test. Hodgdon 335 didn’t do much better, just bettering a 1.25-inch group at 3,227 fps with the maximum load of 31.5 grains of powder. That made Hodgdon Benchmark the clear winner, with 29.5 grains producing a .54-inch group at a slower 3,185 fps.

Groups immediately shrunk while firing Hornady’s 75-grain V-MAX. As well as Benchmark performed with the Barnes, it did poorly with the V-MAX, producing this bullet’s largest groups. Alliant Reloder 15.5 TS produced smaller groups but with pokey velocities, topping out at just 2,628 fps. That left Vihtavuori N-133, which produced respectable velocity and consistent accuracy. The best group measured .45 inch at 3,009 fps using a compressed/ maximum load of 28.5 grains.

Berger’s 80-grain Flat Base Varmint renewed my faith in the HOWA Elevate; not a single group broke an inch, and it produced some of the tightest groups of the entire test. Reloder 15.5 TS produced groups from .51 to .72 inch, but again, provided lackluster velocity. Ramshot TAC was definitely faster all around, hitting 3,074 fps with the compressed/maximum load of 31.5 grains of powder, but its best showing was just .61 inch at 3,012 fps. Accurate 2230 proved the right stuff, producing a .31-inch group at 3,067 fps (30.5-grain maximum load) and .55 inch at 2,946 fps (29.5 grains).

Switching to the H-S Precision Carbon rifle and heavier bullets introduced a touch of more consistency. Hodgdon LEVERevolution provided velocities from 2,823 to 2,896 fps with the Berger 88-grain High BC Flat Base Varmint, but produced no standout groups. Reloder 15.5 TS again proved slow, though it did produce a .54-inch group at 2,571 fps using a compressed/maximum load of 29.5 grains. Accurate 2460 proved best with this bullet, the tightest group measuring .56 inch center-to-center at a respectable 2,911 fps.

Sierra’s 95-grain Tipped Match-King introduced still more consistency but no clear powder winner. StaBALL Match proved a touch slow, but produced the tightest group of the entire test – .30 inch at just 2,640 fps. Alliant Power Pro 2000-MR was consistent across the board, a maximum/compressed load of 32 grains resulted in a .68-inch group at 2,805 fps. Hodgdon CFE 223 produced a .51-inch group with 29.5 grains of powder but at just 2,647 fps.

With Speer’s 100-grain BTSP, LEVERevolution again provided the speed but not the accuracy, the best group printed into .85 inch at 2,729 fps. Hodgdon 4350 is obviously too slow-burning for the 6mm ARC, with velocity topping out at just 2,481 fps with a maximum/compressed load of 30 grains, grouping into .72 inch. Accurate 2700 suffered the same velocity issues but did prove to be more consistent. A .60-inch group at 2,451 fps resulted from 29.5 grains of powder.

With Berger’s 105-grain VLD Target, I expected to see an uptick in accuracy, as the cartridge was designed around such bullets. This didn’t happen, so obviously some seating-depth testing is in order. Power Pro 2000-MR proved consistent, all loads shooting into around ¾-MOA, with a top velocity of 2,664 fps using the maximum/compressed load of 30.5 grains. Accurate 2520 did best with 29 grains of powder, providing a .61-inch group at 2,583 fps. Reloder 15.5 TS hit its stride with the heavier bullet, providing velocities more on par with the other powders auditioned. A .70-inch group was its best showing, leaving the muzzle at 2,507 fps.

These HOWA carbon Minis are fun little rifles ideally suited to varmint shooters who like to hike and especially aggressive predator callers who don’t mind getting away from the vehicle. They are easy to tote, fast handling, and provide more than enough accuracy for the average small varmint or predator shooter. The 6mm ARC also provides enough versatility to cover any varmint hunt, from burrowing rodents to destructive wild hogs.