The 6mm ARC is a flat-shooting (and newer) AR-15 cartridge with little recoil. The 5.56 NATO is the standard AR-15 cartridge, albeit not without significant flaws. In this 6mm ARC vs. 5.56 NATO comparison, we’ll learn if the 5.56 has finally been outdone or if you should keep your AR-15 chambered for it.
Overview of 6mm ARC vs. 5.56 Ammo
The 5.56x45 is beloved by many firearm enthusiasts (myself included), yet despised by others. It’s utilized by militaries worldwide because it is accurate, low-recoiling, and relatively inexpensive to fire. We civilians regularly use it for hunting (including deer in some states, but mostly varmint), home defense, target shooting, and competitive shooting.
The relatively new 6mm Advanced Rifle Cartridge (ARC) is a low-recoil, flat-shooting round that’s ideal for long-range target practice and hunting. It promises to do what the 5.56 can’t (deliver more stopping power), but it also has some downsides of its own (more on that later).
6mm ARC vs. 5.56 Pros and Cons
Neither of these rifle cartridges is perfect, as each has significant advantages over the other.
| 5.56 | 6mm ARC |
|---|---|
| Pros | Cons |
 Lower recoil |
✗ Steeper trajectory | Flatter trajectory |
✗ More expensive/limited availability |
|---|---|---|---|
| Inexpensive, abundant ammo |
✗ Less stopping power for hunting/home defense | Higher ballistic coefficient |
✗ Shorter barrel life |
| Longer barrel life |
— | Better for long-range shooting and target practice |
✗ Slightly more recoil |
| Established and trusted for decades |
— | More stopping power |
— |
6mm ARC vs. 5.56 Ammo Specs
| Category | 5.56x45mm | 6mm ARC |
|---|---|---|
| Parent Case | 223 Remington | 6.5 Grendel |
| Bullet Diameter | 0.224" | 0.243" |
| Neck Diameter | 0.253" | 0.274" |
| Base Diameter | 0.377" | 0.441" |
| Case Length | 1.760" | 1.490" |
| Overall Length | 2.260" | 2.260" |
| Case Capacity | 28.5 grains H2O | 34.0 grains H2O |
| Max Pressure | 55,114 psi (SCATP 5.56) | 52,000 psi (SAAMI) |
6mm ARC vs. 5.56 Recoil and Shooting Experience
The 5.56 has minimal recoil: ~5 ft-lbs of free recoil energy, give or take, depending on which rifle and ammo you’re firing. It’s often surprising to new shooters how little an AR-15 chambered in 5.56 kicks, which is why I typically use it to introduce new shooters to the sport. As an experienced shooter, I enjoy taking my 5.56 rifles to the range because they’re easy on my wallet and my shoulder compared to most other rifle cartridges.
The 6mm ARC has more recoil: ~9 ft-lbs of free recoil energy. While that’s nearly double the 5.56’s recoil energy, it’s still very manageable (15 ft-lbs or less is manageable for most shooters). The main problem with the 6mm ARC is its shorter barrel life: you’ll only get ~5,000 rounds per barrel. Whereas you’ll get 10,000 to 30,000 rounds out of a 5.56 barrel.
Accuracy and Effective Range
In the hands of the average shooter, the 5.56 is very accurate out to 250 yards. When a well-trained individual takes hold of a 5.56 rifle, they can accurately cover up to 600 yards. In military applications, the 5.56 is effective against area targets out to the 600-yard mark. But for deer hunting purposes, its effective range maxes out at ~200 yards.
In the hands of a capable shooter, the 6mm ARC is accurate enough to make 1,000+ yard shots. It can ethically drop varmints at 1,000 yards, too. But for deer hunting, it’s limited to ~500 yards. The 6mm ARC definitely has the advantage in long-range situations.
| Scenario | 5.56 NATO | 6mm ARC |
|---|---|---|
| Average shooter | 250 yds | 600 yds |
| Trained shooter | 600 yds | 1,000+ yds |
| Military area targets | 600 yds | — |
| Deer hunting | ~200 yds | ~500 yds |
| Varmint hunting | — | 1,000 yds |
Penetration and Terminal Ballistics
The 5.56 easily penetrates wood, drywall, and soft tissue, but it doesn’t retain enough energy to ethically harvest medium game beyond 200 yards. Many 5.56 bullets yaw (i.e. tumble) after impact, creating a larger wound channel than the diameter of the bullet. Others (especially FMJs) will fragment apart after impact instead.
The 6mm ARC also easily penetrates wood, drywall, and soft tissue. Unlike the 5.56, it retains enough energy to ethically harvest medium game within ~500 yards. While some 6mm ARC bullets yaw after impact, most hunting ammo is loaded with polymer-tipped hollow point bullets that expand after impact to inflict a larger wound channel.
Continue reading 6mm ARC vs. 5.56 NATO: Does the 6mm ARC Make the 5.56 Obsolete? on Ammo.com
https://ammo.com/comparison/6mm-arc-vs-556#6mm-arc-vs-5-56-hunting