Precision Showdown: 6mm ARC vs. 6.5 Grendel

November 22, 2023 Edited December 12, 2023 13001 view(s)
Precision Showdown: 6mm ARC vs. 6.5 Grendel

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 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. 


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.


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
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. 


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!


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Joseph Superfisky
January 15, 2024
Don't like the ARC. The Grendel is the best small case 6.5 mm round ever made, ! I have liked my last 7 mule deer in Washington state with this round and have built everyone of my hunting buddies a 6.5 Grendel for deer hunting ! We use a 20 inch Bear creek barrel and a bear creek side charging reciever on a Juggernaut billet lower with a rise armament 3.0 single stage trigger and we have a Hera or Midwest 12 or 15 quad rail on it with a bipod, a magpul angled fore grip and a super bright stream light on it for walking in , in the morning and out in the evening and all 4 of us swear by this combination as incredible for Muley’s. Out to 600 , any further and we reach for the crews more we each have as well we all use primary arms scopes on these guns as well because they have one made for the Grendel and it’s awesome! Regards Joe Owner : supwrfly’s outdoor adventure’s And Urban -n- Islands trophy Blacktail hunting
John Evans
February 19, 2024
I would have to agree, the Grendel I bought my son is one slick shooter. I love its hotrod performance with enough bullet weight to take a variety of game at fairly good distances here in North Idaho. I purchased our first Grendel from APF back in 2012 I believe, and was able to purchase a good bulk amount of cheap wolf ammunition for plinking back then and Alexander Arms premium to hunt with. I am picking up a couple more Grendel uppers from BCA for my other two sons. Happy Hunting
February 27, 2024
The 6.5 does it all...accurate, fast, flat, mild recoil for old and young alike! Just makes sense!
Jeff Benson
February 18, 2024
I’ve been loading the 95 gr V-max bullet in my 6.5 Grendel’s for many years now. I think comparing that bullet combo to the ARC would show different results. I’m a Grendel fan, have no use for the ARC.
Kenneth Brown
February 18, 2024
6.5 Grendel also comes in a 108 gr. load, which has a better performance than 6mm arc. You are biased in your comparison.
Bryan Gruszie
February 19, 2024
I don't have a 6 mm arc. but I do have a few 6.5 Grendel's . I do shoot 1000 yds with a 6.5 mm Grendel out of a 23" Vepr Ak.. very good round . Barns 120 gn bullets with TAC powder, Starline brass is what it likes... I really think Barrel length is key.. My 18" and 16" barrel 's cant cut 1k. I have dropped a large mullie doe with my 16" gun...
Lowell Dodson
February 19, 2024
I've been shooting the 6mm ARC for a couple of years now and took my first deer with it this fall. I've been very impressed with the accuracy, sub MOA at every range I've shot it out to 800 yards. 100 yard groups measure .47"-.78" sense the first sighting in, most of those groups are just single ragged holes. I'm thinking of taking up competitive shooting with this AR-15 setup. I've never owned a gun as sharp as this one. As for hunting, I took my 125lbs doe at around 150 yrds and point of impact was so close to my 200 yard zero I couldn't tell the difference. Recoil is so low I saw the bullet hit the deer and she went down blowing blood out her mouth and didn't take a single step. I wouldn't hesitate to shoot a Mule Deer out to at least 300 yards with it, I wouldn't shoot at anything with any caliber past 500 yards as the time of flight becomes an issue. I can't waie to shoot some yokes with it.
william Lincourt
February 23, 2024
Just received my 6.5 grendel side charging upper. This in my third upper from bca. So far I have had no complaints except the 300 BO was a little picky with mags. Lancer mags work great.
william watson
February 25, 2024
Well ' it's easy to find cheap ammo for the Grendel on line at 100-g ,110g , 120, 123g, and 124g ' - so THE next upper i will purchase from B.C.A . WILL BE THE GREAT GRENDEL ! 24-ICNH Barrel , fluted , left side charge .
Lucas McElroy
April 20, 2024
No such thing as cheap ammo for the Grundie.. even wolf is 70-75 a round.. must hand load for this cartridge.. I do. It’s worth it. BCA, mass produce some cheap steel Grendel for us! Give us some good cheap plinking ammo
Lucas McElroy
April 20, 2024
Why didn’t you use a 100gr projo for the comparison? Doesn’t make much sense. Regardless, love my 20” heavy fluted Grendel from BCA. Sub MOA with good ammo all day. 4” groups at 600yd with 123eldm last weekend. Sub moa today with 100gr normal gtxm @ 100. Love it.. can’t be beat dollar for dollar..
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