I live in the woods in west-central Indiana. The trees are beautiful now, as I write this. It’s late fall and just about time to go into yon woods to seek my deer. (The huge buck that smacked my truck bumper the other night doesn’t count). Ranges are short-to-medium… a rifle spitting 6mm bullets is just about perfect. Also just about perfect are two really popular rifle rounds, the 6mm ARC and the 6.5 Grendel. Let’s see why…
History of the 6mm ARC
Introduced by Hornady in 2020, the 6mm ARC (Advanced Rifle Cartridge) came about per a request from a military organization for a low-recoil, long range AR-compatible rifle round. It was to be used in the DoD’s multi-purpose combat rifle program. The ARC uses high ballistic coefficient 6mm bullets, which helps ensure great performance at long ranges. It typically bests the 6.5 Grendel because of its lighter bullets moving faster. In terms of AR compatibility, the ARC can use magazines made for the 6.5 Grendel. It also shares the ability, along with the Grendel, of being chambered in short, mini-action bolt rifles.
History of the 6.5 Grendel
I’ve written about the Grendel before. So have others… it’s a popular round. It has an interesting backstory, what with being named after a mythical beast from the medieval poem Beowulf.
Armorer Bill Alexander perfected this cartridge, with help from competitive shooter Arne Brennan, and Lapua ballistician Janne Pohjoispää. It was unveiled in May of 2003. Its performance was, to put it mildly, a big hit. It outshot the 7.62 NATO with half the recoil and remained supersonic out to 1200 yards. It has since been chambered in bolt actions and several semi-autos. It is still going strong, with many organizations and individuals using it for varied purposes.
Similarities and Differences
Both of these cartridges were based on the .220 Russian case, and both use the same bolt face. The 7.62x39 is a member of this bolt face club as well.
Another similarity is the cartridge's overall length. Even though the diagram below shows the Grendel as having a C.O.L. of 2.250”, it is typically loaded to the same 2.260” length that the ARC shares.
Differences would include overall case length and (obviously) bullet diameter. Here are two diagrams from Loaddata.com that help illustrate these points…
The 6mm ARC case length is 1.490”, and the Grendel stretches that length to 1.515”. Bullet diameter is the next difference… the Grendel uses a .264 caliber bullet, while the ARC’s bullet diameter is .243.
So, the Grendel uses a case that is .0025” longer, and a bullet that is .003” wider. Not exactly huge differences, but they matter.
Ballistics
I did a lot of checking online about the ballistics between these two calibers since I had no rifles available for me to try. I will summarize ballistics info about the two cartridges by way of three handy charts, from the above site. They’ve done the heavy lifting…
We will look at velocity, energy, and trajectory between the two and then see what we can see from the charts in terms of a summary.
| Velocity | ||
| 6.5 Grendel | Muzzle Velocity (fps) | 300-yard Velocity (fps) |
|---|---|---|
| 123-gr SST | 2,580 | 2,090 |
| 123-grELD Match | 2,580 | 2,090 |
| 123-gr Frontier | 2,580 | 2,090 |
| Average | 2,580 | 2,090 |
| 6mm ARC | ||
| 103-gr ELD-X Precision Hunter | 2,800 | 2,288 |
| 105-gr BTHP BLACK | 2,750 | 2,260 |
| 108-gr ELD Match | 2,750 | 2,265 |
| Average | 2,766 | 2,271 |
| Energy | ||
| 6.5 Grendel | Muzzle Energy (ft-lbs) | 300-yard energy (ft-lbs) |
| 123-gr SST | 1,818 | 1,193 |
| 123-gr ELD Match | 1,818 | 1,193 |
| 123-gr Frontier | 1,818 | 1,083 |
| Average | 1,818 | 1,156 |
| 6mm ARC | ||
| 106-gr ELD-X Precision Hunter | 1,793 | 1,197 |
| 105-gr BTHP BLACK | 1,763 | 1,190 |
| 108-gr ELD Match | 1,813 | 1,230 |
| Average | 1,790 | 1,206 |
| Trajectory / Bullet Drop | |
| 6.5 Grendel | Drop at 400 yards when zeroed to 200 (inches) |
| 123-gr SST | 25.3 |
| 123-gr ELD Match | 25.3 |
| 123-gr Frontier | N/A |
| Average | 25.3 |
| 6mm ARC | |
| 103-gr ELD-X Precision Hunter | 21.8 |
| 105-gr BTHP BLACK | 22.4 |
| 108-gr ELD Match | 22.4 |
| Average | 22.2 |
OK. Looking at the velocity chart, we see that, even at 300 yards, the ARC bests the Grendel by about 180 fps. Part of this is due to its 20-grain-lighter bullet, but other factors kick in as well. One such factor is bullet diameter. The little-bitty .003” difference isn’t much, but one foot-second is one foot-second… The bullets themselves are similar in terms of construction and B.C.
The second thing to look at is energy. We see that the ARC beats the Grendel by 28 ft/lbs at the muzzle, but that number goes up to 50 at 300 yards. The ARC’s tendency to hold on to velocity pays a small dividend in terms of energy. That might make a difference to hunters… I’m not so sure about target shooters.
Lastly, we look at the bullet drop between the two. Assuming a 200-yard zero, the Grendel will drop 3.1 inches more than the ARC at 400 yards. A good shooter will not be flustered by this, but if you are just getting into the 400-plus yard shooting game, you’ll want every advantage you can get.
I’ll leave it to you astute readers to draw your own conclusions from these tables. I thought I knew which of the two I’d pick… until I did more checking. I hadn’t factored cost per round or ammo availability into the mix. Raw data is fine, but if you can’t find the ammo to shoot, all the numbers in the world are pretty meaningless.
6mm ARC vs 6.5 Grendel Cost
It’s time to address the cost of these two rounds. I’ll use Midway USA as the yardstick, as they sell tons of ammo and typically have decent prices. I’ll round the prices off to the nearest dollar. I only looked at what was actually in stock at the time of this writing. “Box” = 20. You might well find better prices, especially for quantity purchase, but this is a start.
6.5 Grendel Cost
The 6.5 Grendel runs from 1.50/round (Hornady Black, 123 ELD, $30/box) to $3.20/round (Underwood Controlled Chaos 110-grain Lead-Free, $64/box). There were 12 loads shown, so you do have some choice as to what you can buy.
6mm ARC Cost
6mm ARC ammo starts at the same $1.50/round (Hornady Black 105 HP Boat Tail Match, $30/box). It tops out at $1.60/round (Hornady V-Match Ammunition 6mm ARC 80 Grain ELD-VT Polymer Tip, $32/box. Midway shows a total of four ARC loads, but two of them are out of stock, no backorder.
If you’re a 6.5 mm/.26 caliber fan, there’s always the Creedmoor (in addition to older 6.5 mm cartridges). Checking the bulkammocheap site shows over 1800 loads for sale, starting at 97 cents/per round. That brings the cost down. For the same price as the .243 Winchester, you can pick up a complete 6.5 Creedmoor upper and get ready to head to the woods.
Either of these rounds work well for deer-sized game out to reasonable ranges, and the Creedmoor can really reach out and touch something way out past the .243’s effective range.
Conclusion
For rifle shooters who want an AR in one of the latest, fastest, calibers out there, the 6mm ARC makes sense. If you can afford to feed it, it will repay you with really fast velocities way out there, and will definitely take down deer-sized game at long range.
Looking for a 6mm ARC? You can pre-order one from us here!
If you like the 6.5 caliber and its bullet selections, the Grendel has proven itself to be a winner for several years now. Also, the ammo selection is greater and a little less expensive than the ARC. Each caliber comes with trade-offs, but either will do the job. You just have to decide which way you want to go… faster/more expensive, or a bit slower/more available. The choice is yours. I hope you enjoy the selection process!
