The release of the new Hornady 6mm ARC (Advanced Rifle Cartridge) supports the perception that gun and ammo makers are engaged in a race to the bottom. Fast is better but slow means mo?
The Hornady 6mm ARC takes the 24-caliber into record territory — the slowest muzzle velocity of any commercial cartridge propelling .243” bullets.
Hornady 6mm ARC Losing Ground
Hornady is claiming its 6mm ARC will yield 2,750 fps with a 108-grain ELD-M bullet from a 24-inch barrel. The old 243 Winchester can beat that by about 300 fps. The 6mm Rem. can exceed it by 500 fps and the 240 Weatherby by 600 fps. We’re going backwards!
If this development strikes you as the opposite of progress, you might have spent the bulk of your life in the 20th century. That was the era of increasing muzzle velocity. This made sense. The faster a bullet leaves the barrel, the farther it flies before hitting the ground, the less it deflects in crosswinds, and the more energy it carries when impacting the target. Advantage, magnum.
Magnum Race Still Being Run
Truth be told, the magnum race is still underway. (Or at least the hyper-velocity race, since “magnum” is poorly defined, as this blog post explains.) Consider the 7mm, 300, 338, and 375 Remington Ultra Magnums. How about the 26, 27, 28, and 30 Noslers? There is no “magnum” behind those titles, yet they are fastest or close to fastest in their calibers. Then there’s Hornady’s new 300 PRC, Weatherby’s 6.5-300 Weatherby, and several more modern speed demons. But at the same time we’re seeing the 6.5 Creedmoor and 6.5 Grendel; the 6.8 Rem. SPC; the 300 AAC Blackout, 350 Winchester Legend and 458 Bushmaster. All of these are heading in the opposite direction. What explains that?
The laser rangefinder, in part. Once lasers hit the fields, the game began to change. Once we could pinpoint exact distance to target, maximum velocity didn’t matter as much. A memorized trajectory curve combined with a ballistic reticle or turret dialing could compensate.
Then the AR-15 platform exploded and the game changed some more. Shooters needed cartridges that would fit these increasingly popular, super-short actions.
Finally, we started seeing heavy, high B.C., very low drag bullets that improved trajectories by minimizing drag and conserving energy. This colored our perception of lower velocity rounds. Thanks in large part to new, long-range shooting competitions, our acceptance of lower velocity accelerated even as muzzle velocities decelerated…
Wait a minute. How do lower velocity cartridges improve long-range shooting? Or hunting? Or anything? Let us count the ways.
8 Benefits of Hornady 6mm ARC and Other Slow Rifle Cartridges
- Low velocity coupled with relatively light bullets reduces recoil. Reduced recoil minimizes flinching and enables shooters to see their hits or misses so they can correct for subsequent shots.
- Lower velocity means less flame and heat for longer barrel life. When you’re shooting dozens and dozens of rounds in a single competition, barrel life matters.
- Low velocity from a short cartridge means it fits in a shorter, potentially stiffer action which can contribute to increased accuracy. Or it fits the extra-short AR-15 platform rifles beloved and preferred by many shooters.
- Short, relatively fat cartridges concentrate powder near the ignition flame for an even, consistent burn with a tendency to improve muzzle velocity consistency. MV consistency matters a great deal at extended ranges.
- Short, fat cartridges leave room for long necks that hold long, high B.C. bullets straight and seated above the powder reservoir. The high B.C. projectiles make up for their lower MV with less wind deflection, the toughest variable to battle at long range.
- Some smaller capacity, low velocity rounds are tailored for sub-sonic, low-report firing for clandestine military engagements. The general shooting public loves them for control of vermin like feral hogs.
- Soft-report, low-recoil cartridges prove ideal for starting new shooters, many of whom never see the need for escalation. Why step up to a loud, hard-kicking 300 PRC when you’re dropping your deer with your 6.5 Grendel as far as you can shoot in your hunting field?
- Straight-wall rounds like Winchester’s little 350 Legend may be the only centerfire rifle cartridges legal for deer hunting in some states, so of course they’re going to be popular.
There you have it. Eight reasons to embrace the Hornady 6mm ARC and other low-velocity cartridges. You may know one or two more. And one may be all you need to justify a new rifle in a new, low velocity chambering. In many ways, the race to the bottom is paying off.
Hornady 6mm ARC Details
The 6mm ARC is basically the 6.5 Grendel necked down to hold a .243” bullet with the 30-degree shoulder pushed back a smidgen. Its release as a commercial round was presaged by a number of successful 6mm wildcats like the 6mm AR based on the Grendel.
Maximum Cartridge Overall Length is 2.26”. Head diameter is .441”, a bit less than the .535″ head of the short-lived 243 WSSM which was a lot faster than the ARC. Unlike the WSSM, the Hornady 6mm ARC was engineered around a long, high B.C. .243 bullet for military (combat) applications in modern, autoloading rifles. As such, SAAMI maximum average pressure is set at a relatively mild 52,000 psi. Twist rate is 1:7.5” to stabilize the long 105- to 108-grain high B.C. bullets. (roughly .530 to .540 B.C. range.) To keep the 115-grain Berger VLD (G1 B.C. .563) from wobbling, the 6mm ARC will need at least a 1:7 twist. Full house loads will likely burn about 27- to 29-grains of suitable powders such as H4895, Reloader 15, and AA 2520, so handloads should be relatively inexpensive to build.
Ballistically, thanks mostly to heavy-for-caliber, high B.C. bullets like Hornady’s 108-grain ELD-Match, the Hornady 6mm ARC drops and drifts less than any 223 Rem. It recoils about 50% less than any long-range 308 Win. It stays supersonic farther downrange than the 308 Win. and puts more impact splash on steel plates than any .224 rounds. It’s also legal for deer hunting in more States and arguably more effective.
Nearly two dozen rifle makers are already chambering for the round, including Browning, Proof, Christensen, Barrett, Mossberg, and Howa. I’m thinking most, if not all of these are bolt actions, but there are plenty of AR rifles ready to chew up a few thousand 6mm ARC rounds for you. Check one out and join the race to the bottom. You might be surprised to discover you’ve come out on top!
The author marvels at the gun industry’s ability to create ever more cartridges that keep the shooting sports fresh.