Finding the right cartridge for your rifle can be challenging, but even more so when you’re torn between the 5.56 vs. 6.5 Grendel—you wouldn’t want to make the wrong choice. With our experts’ help, the process becomes simpler. Read what we found out through our thorough testing of both cartridges.
6.5 Grendel or 5.56?
In-Depth Comparison: 6.5 Grendel and 5.56
The 6.5 Grendel utilizes a shorter, bigger diameter case for higher powder proportion while allowing space for long, streamlined, and high ballistic coefficient bullets.
It has a diameter of 7.62 ×39mm and 6.5mm PPC cases, which is larger than that of a 5.56 and necessitates a non-standard AR-15 bolt. The 6.5 Grendel is an upgrade to the 6.5mm PPC.
The 5.56 contains a steel penetrator that can shoot through about 38 to 50 cm soft tissue in ideal circumstances.
The 6.5 Grendel has a minimal recoil that attains distances beyond 500 yards. Depending on their case material and bullet, 6.5 Grendel cartridges weigh 14.7 to 17.8 grams (227 to 275 gr). This makes it great for long-range shootings.
The 5.56 has a minimal recoil too. However, our team found that the 5.56 recoil depends on the weight of the rifle from which it is being fired. Firing from a 5.7kg rifle, the 5.56 reported less recoil than the 6.5 Grendel.
(The same is observed in the 6.5 Creedmoor when it was compared against the 6.5 PRC.)
The 5.56 is a rimless bottlenecked intermediate cartridge with a cartridge case capacity of 1.85ml (28.5 grams H20) and a case length of 44.70mm (1.760 in). It has a cartridge dimension of 5.56×45mm and can withstand a pressure up to 430.0 MAP (62,366 psi) Piezo service pressure.
The 6.5 Grendel is also a rimless bottlenecked cartridge measuring 57.5mm overall. The case is 38.7mm long. With a 6.7mm bullet diameter and a rim diameter of 11.2mm, the cartridge produces a minimum average pressure of 52,000psi.
The effective range of 5.56 with a 20° barrel is 400 meters. However, the 6.5 Grendel has a little less range than the 5.56. It has an effective range of 360 meters.
The 6.5 Grendel is found within the range of 510 ballistic coefficients (BC) while the 5.56 has a ballistic coefficient of around 400. (We also made comparisons on other ammo, such as the 300 Blackout and the 350 Legend.)
What is the implication of this? The ballistic coefficient (BC) is a measure of how aerodynamic a bullet is, with the higher being better.
This implies that the 6.5 Grendel with a higher ballistic coefficient (510) will drift less in the wind, lose velocity more slowly, and generally be more accurate at long range and in the wind compared to the 5.56 which have a ballistic coefficient of 400.
The 6.5 Grendel has a higher sectional density when compared to 5.56. This is simply how “long and thin” vs. “short and fat” a bullet is.
The 6.5 Grendel vs 5.56 is longer and thinner in appearance. Because of the higher sectional density, the 6.5 Grendel has a higher ballistic coefficient than low sectional density  bullets like the 5.56.
In terms of terminal performance, the 6.5 Grendel retains more incredible terminal energy when shot at extended ranges than the 5.56 due to its higher ballistic coefficient.
The 123gr (8.0 g) 6.5 Grendel has more energy and better armor penetration at 1000 meters than the 5.56, which has a lower stopping power, lethality, and range.
Obviously, in terms of terminal performance, the 6.5 Grendel will deliver a higher terminal performance than the 5.56.
(Interested in more cartridges? See how the 458 SOCOM and the 308 Winchester performs side-by-side.)
5.56 or 6.5 Grendel for Hunting?
When hunting, the emphasis is laid on picking the appropriate bullet as efficiency and hitting the target in the farthest distance, and the first time is vital.
The 5.56, because of its low sectional density, is too small or too light to ensure deep enough penetration and enough cavitation to kill a target animal like deer. If a 5.56 is used, there is the chance of the deer running a long-distance before dying a slow, agonizing death. We want to avoid that in our hunting expedition.
The 6.5 Grendel, on the other hand, is the ideal bullet size for hunting because of its excellent sectional density, which gives rise to significant penetration. Here’s the kicker: The 6.5 Grendel results in intense cavitation into the wound track because of its weight, alongside its low recoil ability, which aids shot placement.
5.56 or 6.5 Grendel for Combat?
Having just one multifunctional cartridge in terms of range (long and short) is vital for combat. The 6.5 Grendel was manufactured as a hunting cartridge that would extend the effective range of an AR.-15 cartridge. It has double the recoil but slightly less capacity than the 5.56, and the velocity is too low.
The 5.56, on the other hand, specializes in close-quarter combats because it was specifically designed to be highly lethal at close range. It’s low recoil, and high lethality makes it perfect for close-range combats.
Still, low-sectional density produces relatively poor performance when faced with barriers, and barriers are unavoidable in combats, leading our team to determine the 5.56 to be the winner in this category.
Does 6.5 Grendel use 5.56 lower?
6.5 Grendel uses 5.56 lower. The only things that are not the same are the barrel and bolt. The upper, lower, gas system, carrier, among others, are the same and can be interchanged.
Overall Winner: 6.5 Grendel
The 6.5 Grendel, with its ballistic coefficient (510), makes it drift less in the wind and lose velocity more slowly. It is also more accurate at targeting long-range.
Its long and thin feature increases the sectional density, which makes it an ideal bullet size pick for hunting. The versatile design makes it retain more terminal energy over long ranges than the 5.56 due to its Ballistics Coefficient.
The 6.5 Grendel is also ideal for combat because of its weight, making it effective for navigating more extended range and going past barriers.