6mm ARC vs. 6.5 Grendel is a worthy debate, as both cartridges share the same parent case.
Both were also designed for the AR-15 platform for similar reasons, so which one does the job better? It all boils down to your intended purpose.
Cartridge Specs
The 6mm ARC and 6.5 Grendel both originate from the .220 Russian, so there is very little difference between them. Even experienced shooters will have difficulty telling the rounds apart at first glance.
| Category | 6mm ARC | 6.5 Grendel |
|---|---|---|
| Parent Case | 5.6Ă—39mm | 6.5mm PPC |
| Bullet Diameter | 0.243 in | 0.264 in |
| Neck Diameter | 0.274 in | 0.293 in |
| Base Diameter | 0.441 in | 0.439 in |
| Case Length | 1.49 in | 1.52 in |
| Overall Length | 2.26 in | 2.26 in |
| Case Capacity | 34 grains | 35 grains |
| Max Pressure (SAAMI) | 52,000 psi | 52,000 psi |
6.5 Grendel vs. 6mm ARC Recoil
Neither round is known for having high recoil, although the 6mm ARC doesn’t kick as hard as the 6.5 Grendel. It has 9 foot-pounds (ft-lbs) of recoil due primarily to its lighter propellant charge and lighter projectiles.
The 6mm ARC has a slight advantage in recoil.
Trajectory
Shooters generally prefer a flat-shooting round over one that requires a great deal of compensation for bullet drop. That’s why 6mm bullets are so popular among medium-to-long-range shooters. They’re known to coast across flat trajectories.
The 6mm ARC is loaded with more aerodynamic bullets than the 6.5 Grendel. At 400 yards, it has an average bullet drop of 22.2 inches.
Bullet drop for the 6.5 Grendel is slightly steeper because its bullets are more massive. Even so, 25.3 inches of drop at 400 yards is by no means terrible.
The 6mm ARC has a flatter trajectory by 3.1" at 400 yards. The difference in bullet drop will become more pronounced as we extend the distance. Regardless, both rounds are excellent for long-range shooting.
The winner is the 6mm ARC, albeit by a narrow margin.
Accuracy
Accuracy is defined as how close the bullet hits the target compared to where the shooter aims. While accuracy is largely influenced by the cartridge and its bullet, it is also determined by the shooter, rifle, barrel length, and optic.
The 6mm ARC and 6.5 Grendel are so similar that I seriously doubt whether you would notice any difference between them (assuming all other factors are equal).
Some people are more accurate with a lighter-recoiling firearm, whereas others aren’t as bothered by recoil and can be as accurate with a rifle that kicks harder. With that in mind, this category is a tie.
Continue reading 6mm ARC vs. 6.5 Grendel: Which AR-15 Round Is Better? on Ammo.com
https://ammo.com/comparison/6mm-arc-vs-6.5-grendel#6mm-arc-vs-65-grendel-at-1000-yards