6.8 SPC vs 6.5 Grendel have been rivals since they hit the market. With so much in common, it’s no wonder that you may not be sure which is right for you.
From the history of the cartridge to the ballistics, we’ve got all the information that you need!
A Bit Of History
Ever since the .223/5.56 NATO cartridges were invented, people have been trying to replace them. Don’t get me wrong, 5.56 NATO is a great cartridge and it covers a lot of ground. But there are a lot of bad guys in the world who aren’t with us anymore proving the effectiveness of that little round.
But even on its best days, 5.56 NATO is a bit lacking when it comes to raw energy.
There have been a dozen or more attempts to solve this with a new cartridge, but few have come close to succeeding. Two that came pretty close are 6.5 Grendel vs 6.8 SPC.
6.5 Grendel
I enjoy talking about this great cartridge and mentioning that it was invented by Bill Alexander from Alexander Arms. Named after the monster that attacks Beowulf's mead hall in the poem Beowulf.
While the cartridge is awesome, the story gets a little… weird after that.
Normally, when a new cartridge is invented, and want anyone to use it. You must submit specs to SAAMI, an industry organization that standardizes ammo and chamber specs for approval and standardization. Part of that process requires that you release any copyrights and trademarks to the ammo and chamber design.
Bill Alexander didn’t do that (at the time) and chose to keep his copyright on the 6.5 Grendel.
To get around this, Les Baer slightly modified the barrel and bolts they sold. This way they weren't the same as the 6.5 Grendel specs.
For reasons I don’t fully understand, the Les Baer version became known as “Type 1.” While the Alexander Arms version was called “Type 2.”
This has led people to think that maybe Type 1 is the OG… it isn’t.
Eventually, Alexander Arms submitted the 6.5 Grendel to SAAMI for approval. In doing this, they released their trademarks and copyrights.
This is awesome for us shooters since the Type 2 Grendel is the better, stronger, version.
While there are still Type 1 bolts and barrels floating around out there, it’s uncommon to come across one.
Bear Creek Arsenal exclusively uses the Type 2 6.5 Grendel barrel and bolts.
6.8 SPC
With an objectively less cool name, 6.8 Remington Special Purpose Cartridge has a decently cool backstory.
Designed by Remington with the help of the Army Marksmanship Unit and Special Operations Command (SOCOM). The 6.8 SPC was created for the special operations units. Who requested a cartridge more powerful than the standard 5.56 NATO.
High-speed tactical teams in the Army Delta Force and Navy SEALs needed a way to make their M4s more lethal.
Keep in mind that the 5.56 NATO was designed for 20" barrels. While the M4 uses a 14.5” barrel and barrels even shorter than that are not uncommon within SOCOM.
While cartridges like 300 Blackout and 7.62x39 work wonderfully from a short barrel. The 5.56 NATO loses a lot of velocity and energy from short lengths.
6.8 SPC was one answer to this problem.
Unfortunately, the team rushed the development, and pressure issues during military testing killed the project.
With no official results, there have been anecdotal reports from guys using the 6.8 SPC upper in the field during the GWOT that liked the cartridge.
While it failed to be adopted by the US Army. The LWRCI continued the development of this cartridge and a special AR-15 resulting in their Six8 line of rifles.
The Royal Guards of Jordan and Saudi Arabia adopted the Six8. Sweden’s SOG, similar to the American Navy SEALs, also uses it. The UK’s special forces and the Pentagon Force Protection Agency have adopted it too.
Practical Applications
These two cartridges are very similar. So, we're going to discuss about both at the same time since they cover the same ground.
Hunting
Both 6.8 vs 6.5 are wonderful AR-15 hunting cartridges. They deliver 30-40% more energy than 5.56 NATO in similar barrel lengths and can take deer-sized game out to 250-300 yards with ease.
Both cartridges also have widely available ammo designed for hunting and taking down game.
Long Range Shooting
6.8mm SPC was primarily designed to improve lethality of the M4 at close range. Performing very well out of a longer barrel and with more velocity.
6.5 Grendel AR is another awesome distance plinker that stays supersonic out to 1,000 yards with a 24”ish barrel.
Both are accurate, do well in the wind, and offer little recoil to help you stay on target and track your shots.
6.5 Grendel has better ammo options and generally a higher ballistic coefficient.
Home Defense
While both of these cartridges can be used inside the home. I would not recommend it unless you have zero concern for overpenetration.
For many of us, our pets, family, and neighbors are close by. The 6.5 Grendel and 6.8 SPC can have too much potential for overpenetration. Making them less suitable for home defense.
Both cartridges pack a punch at the muzzle even from short barrels, but both will sail through drywall.
If you live in a home that doesn’t have these concerns. These cartridges offer a major boost in energy on target without a major increase in recoil or handling.
Ballistics
The bottom line, the 6.5 vs 6.8 SPC perform almost identically. Because of comparable barrel lengths, bullet design and bullet weight.
The 6.8 SPC is equipped with a .277" diameter bullet, while the 6.5 Grendel features a .264" diameter bullet.
6.5 Grendel shooting Hornady 123gr SST from a 16” barrel flies at around 2,450 FPS.
6.8 mm shooting Hornady 120gr SST from a 16” barrel flies at around 2,460 FPS.
At 16” these cartridges are neck and neck with each other. However, once you get shorter or longer things change slightly.
For a short barrel, let’s say 12”, 6.8 caliber starts to gain an advantage and sends that 120gr SST at around 2,380 FPS. 6.5 Grendel sends the 123gr SST from a 12” barrel at something around 2,250 FPS.
But on the other end, 6.5 Grendel AR15 tends to gain more velocity from longer barrels. Again, the 123gr SST out of a 24” barrel moves at around 2,580 FPS. 6.8 SPC sends a 120gr SST from a 24” barrel at just 2,520 FPS.
While 6.8 SPC performs “better” with short barrels, the 6.5mm Grendel performs “better” with long barrels. However these differences are barely noticeable.
The biggest difference is when using a short barrel, if you want the most punch at closer ranges 6.8 SPC is a better choice. But honestly, I very much doubt that anything you shoot will go down to ~1500 ft.lbf when it wouldn’t go down to ~1,400 ft.lbf.
Ammunition Choices
The biggest difference between these cartridges is how the market has decided that 6.5 Grendel is more popular.
For whatever reason, 6.8SPC just never really caught on. And while it took 6.5 Grendel a minute, it has really taken off.
Maybe because there is already a boatload of super popular 6.5mm cartridges and projectiles on the market. Or, maybe it’s because Grendel is a way cooler name than Special Purpose Cartridge.
Either way, the bottom line is that 6.5 Grendel has a LOT more variety in ammo choices.
The 65 Grendel has everything. It offers super cheap steel-cased plinking rounds. It also has high-end match-grade long-range precision rounds. Plus, it includes every type of hunting bullet ever made.
You can even find it in stock at most local brick-and-mortar stores.
6.8 SPC has a fairly impressive selection of hunting rounds that are pretty easy to find in stock, but that’s about it. The low-end cheap ammo doesn’t exist for 6.8 SPC and the high-end match-grade ammo is really hard to find.
Prices between the two cartridges are fairly even if you’re looking at similar ammo. But the 6.8 SPC tends to be slightly more expensive in general.
Build Or Buy
If you’re looking to build an AR-15 for either cartridge, you’re in luck because it’s super easy.
Both 6.8SPC vs 6.5 Grendel only require a new barrel, new bolt, and new magazines. They do not interchange with each other, but people use them for some other cartridges. Regardless of making them a more popular and easier to find.
Cartridges like 6mm ARC use the same bolt as 6.5 AR Grendel while .224 Valkyrie uses the same bolt as 6.8 mm Remington. So if you already have one or the other, you’re halfway home to making a new upper!
Ensure the barrel fits the cartridge you want. Since the barrel and chambers are not interchangeable with any other cartridge.
If you’re looking to just buy a new upper… then do it! As with most things, AR-15, a new complete upper, and some new magazines and you’re good to go.
What Is Best For You
Maybe I’m a bit biased, but unless you’re just interested in 6.8 mm SPC, the 6.5 Grendel wins.
6.8 SPC isn’t bad and it has respectable strengths, but simply hasn’t caught on like 6.5 Grendel has.
Both cartridges offer comparable ballistics and are wonderful platforms for reloading and really maximizing what they can do, with decent magazine and parts support.
But 6.5 Grendel has a lot more reloading and a lot more factory ammo options. Since 6.5 Grendel does 99% of what the 6.8 does, it has order of magnitude more options to meet your needs. Making the Grendel a better overall option if you prioritize long-range performance, and a flatter trajectory.
On the contrary if you give priority to less recoil and great close-range performance, the 6.8 SPC is your best choice.
Wrapping Up
Both of these cartridges are pretty awesome and both will serve you well. The biggest difference is simply that 6.5 Grendel is more popular and has more support. If you want to buck the trends, get a 6.8 SPC and have at it.
For ease of components, ammo, and rifles 6.5 wins hands down. Grendel also has a cooler name, so let’s face it -- that’s really what matters most.
