6.8 SPC or 6.5 Grendel, which is the better all-around cartridge for the AR-15 platform?
Man, that seems to be the question I hear the most recently. So, first, lets do a brief history on the two cartridges, and look at their designed uses.
The 6.8SPC was initially designed as a round to increase the lethality of Short Barreled Rifles/Carbines as a way to possibly replace the 5.56 NATO round for military purposes and designed by Remington Arms in collaboration with the US Army Marksmanship Unit and the US Special Operations Command around 2004. The round generates velocities between 2400 feet per second up to about 3000 feet per second depending on the bullet weight used.
The 6.5 Grendel was designed to be an effective 0-800 yard cartridge that stayed within the dimensions of the AR-15/M-16 magazine length, surpassing the performance of the 5.56 NATO/.223 Remington. To do that, the designers used a shorter, fatter case allowing higher powder capacity while still allowing the long 6.5mm bullets to be seated to a normal operating length for the magazines of the weapons. Velocities for the round are almost identical at 2300 feet per second up to 3000 feet per second depending on bullet weight used.
BOTH of the cartridges require the operator to use a special barrel, bolt, and magazines compared to the standard 5.56 NATO to use them.
Bullet weights available for use in the 6.8 SPC to work in semi-auto firearms ranges from 85 grains up to 120 grains for use in magazine fed firearms. For the 6.5 Grendel, the weights available range from 85 grains up to 155/156 grains.
Now for the pros and cons of the two cartridges.
Pros – Larger bullet weight selection if you are a reloader and for factory loads, weight for weight 6.5mm bullets have a higher sectional density which means they hold together better on impact than the same weight 6.8 bullet, higher ballistic coefficients per bullet weight means better retained velocities and energy at all distances, ammo is available in the 6.5 Grendel that can be had for less than $5.00 a box of 20 making it much cheaper to shoot than the 6.8 and even most 5.56 NATO for target shooting days, has been adopted by the Serbian military as their main caliber for armed forces, and is in technical testing for US Special Forces.
Cons – Requires a different bolt and magazine than the 5.56 NATO, so higher cost to convert a rifle, currently not as many commercial factory ammunition choices as the 6.8 SPC.
Cons – Exterior ballistics inferior to the 6.5 Grendel in every aspect, requires different bolt and magazine than the 5.56 NATO, so higher cost to convert a rifle, no inexpensive target shooting ammo or bullets for reloading.
My conclusion, as an all-around cartridge, the 6.5 Grendel is the clear winner. It has better ballistics from 0-800 yards, has more available options for bullets, and can drive those bullets to the same speeds or better than the 6.8 SPC. The ONLY place I have seen the 6.8 best the 6.5 is when the barrel lengths get below 14 inches, but, that isn’t an option for those of us residing in the state of Kommiefornia.
Keep your powder dry, Jim.
written by Jim Hanson