Both the 6.5 Grendel and the 6.8 SPC are powerhouses that took AR to next-level heights. But the question remains – which really is the better cartridge? This debate has gone on for far too long that we’ve decided to take matters into our own hands to give you a head-to-head comparison.
6.5 Grendel Advantages
6.8 SPC Advantages
Features of Both Ammo
Having been around for more than a decade, the 6.5 Grendel has established a firm footing in the military and the community of shooters. It’s an intermediate cartridge that’s designed for the AR-15 platform and is considered a great battlefield cartridge.
Introduced to the market by Alexander Arms, the 6.5 Grendel is based on the Soviet’s military 7.62x39mm M43 design plus the 6.5mm PPC rounds. It was further developed by the company for greater sectional density and accuracy.
As for the 6.8 Remington Special Purpose Cartridge (SPC), it came to the market only a year earlier than the Grendel. Its development is focused on making a cartridge that ‘fixes’ the imperfections of the 5.6mm.
The Remington Arms Company, in partnership with the Army Marksmanship Unit, utilized a shortened .30 Remington case necked down in order to shoot a 6.8mm. After some time, the 6.8 SPC received its SAAMI approval in 2004.
While it was substantially more powerful and more lethal than the 5.56x45mm cartridge, the 6.8 SPC had a terrible roll-out because the 6.8 SPC rifles had a poor chamber design. Remington came to the rescue and fixed the issues, but it was different from the spec design that SAAMI initially approved.
As such, the SAAMI specs are still the old chamber dimensions, making most ammo options designed for the original SPC specifications. This has affected the ballistic performance, but the 6.8 SPC II chambers can handle hotter loads and give a performance that reaches the potential of the cartridge.
At first glance, the 6.5 Grendel and 6.8mm SPC look similar. Their overall length is the same at 2.26”, which goes right to the limit that fits an AR-15s. However, there are also crystal clear differences between these two cartridges.
First, their rim diameters differ. The 6.5 Grendel is at .438” while the 6.8 SPC is at .422”. Second, they also use different diameter bullets—the Grendel at .264” and the SPC at .277”. And third, the bullet weights are not the same. The Grendel uses bullet weights in the 90-130gr range, while the 6.8 SPC uses 75-120gr range.
With this, the Grendel is a flexible caliber because it’s available in a large selection of bullet weights. Because it uses .26/6.5mm bullets, it has a wide selection of high BC bullets that are ideal for varmint hunting or small game hunting on a greater range. However, the 6.8 SPC does have a bigger assortment of hunting bullets  compared to the 6.5 Grendel.
In our tests for the 6.8 SPC vs. 6.5 Grendel, there really isn’t much of a difference between both. Taking note that we used 123gr for Grendel, 120gr for SPC, and 16” barrels, their trajectories were almost the same.
The 6.8 SPC does start out faster but the trajectory was almost identical at 250 yards. At 500 yards, the 6.5 Grendel took the lead and was faster at 500 yards. That being said, it’s almost the same until the distance reaches about 500-600 yards.
So even if the SPC started at 100 FPS faster, both were on an equal field for a long way. That’s because the Grendel is more aerodynamic and easily catches up with the SPC.
However, if you do bump up the barrel length used, you’ll see a substantial lead with the Grendel. And this is a big point worth mentioning, because the dwindled performance of the SPC on barrels longer than 16” is both a blessing and a curse.
You will get an excellent performance from the 6.8 SPC if you use shorter barrels. But when you use barrels that are longer than 16”, the SPC’s velocity lessens compared to the Grendel.
Then again, that doesn’t really mean that the SPC sucks completely. If you want to use longer barrels and you’re shooting on a longer range, then the Grendel would be a better choice.
Both the 6.5 Grendel and the 6.5 SPC are very lethal cartridges. When we’ve tested the two, they don’t really have an effective difference inside the common hunting range. So whether you’re into varmint, small game, or big game hunting, both can kill nicely and cleanly.
But of course, we can’t set aside the fact that the Grendel is more accurate in long-range shooting. It drops less and drifts less in the wind, particularly because of the high BC. At 500 yards, it drifts 6-7 inches less. At 750 yards, the drift is up to 19 inches less.
That’s a considerable advantage indeed. With the higher sectional density of the 6.5 Grendel, it holds better in the wind and therefore maintains its velocity better than the 6.8 SPC.
Still, it’s very important to note that the difference between the two cartridges don’t show until the 500-yard mark. Most shooters won’t even hit their target if it’s that far away, so if you’re shooting in less range, the performance of the Grendel and the SPC are essentially the same.
Conclusion: 6.5 Grendel or 6.8 SPC?
The 6.5 Grendel vs. 6.8 SPC debate may be a tough one, but that’s just because they’re both great options. In overall performance, there isn’t a wide gap between the two cartridges.
The 6.5 Grendel is ideal for hunting, combat, and long-range shooting. It has a decided advantage when shooting beyond 500 yards, particularly due to its high sectional density.
The 6.8 SPC is a lethal cartridge that is also accurate when it comes to hunting and combat. It has its shortcomings when it comes to long ranges and longer barrels, but its trajectory and performance is similar to Grendel’s.