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 5.56 and 6mm ARC 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. Civilians regularly use it for hunting (including deer, in some states), 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. It promises to do what the 5.56 can’t, but it also has some downsides of its own (more on that later).
5.56 vs. 6mm ARC 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 |
| undefined | ---- | ---- | ---- |
| ✓ Longer barrel life | — | ✓ Better for long-range shooting and target practice | ✗ Slightly more recoil |
| undefined | ---- | ---- | ---- |
| ✓ Established and trusted for decades | — | ✓ More stopping power | — |
| undefined | ---- | ---- | ---- |
6mm ARC vs. 5.56 Ammo Specs
| Category | 5.56x45mm | 6mm ARC |
|---|---|---|
| Parent Case | 223 Remington | 5.6x39mm |
| 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) |
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