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6mm ARC vs 6.5 Grendel: Which AR-15 Round Is Best?

Old 07-06-2022, 01:56 PM
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Default 6mm ARC vs 6.5 Grendel: Which AR-15 Round Is Best?

The 6mm ARC vs 6.5 Grendel is worthy of debate since both cartridges have the same parent cartridge.

Both were designed for the AR-15 platform for similar reasons, so which one does the job the best?

Honestly, it boils down to your intended purpose.

6.5 Grendel vs. 6mm ARC

These two rounds are incredibly similar, so does it matter which one you choose?

We say yes!

However, each caliber has its purpose, so we will break down which caliber is best overall, but we will also give you the circumstances when one is more beneficial than the other.

Cartridge Specs

The 6mm ARC and the 6.5 Grendel originate from the .220 Russian, so there is very little difference.

At a glance, experienced shooters will have difficulty initially telling the rounds apart.

The bullet diameters differ by only 0.021 inches, with the 6.5 Grendel being 0.264 inches while the 6mm ARC is 0.243 inches.

The rim diameter is even closer with only 0.001 inches difference—the 6.5 Grendel is 0.44 inches in diameter, whereas the 6mm ARC is 0.441 inches in diameter.

The 6mm ARC case is slightly shorter at 1.49 inches compared to the 1.52 inches of the 6.5 Grendel case.

The 6.5 Grendel has a broader range of bullet weights, ranging from 90 grains to 130 grains. In contrast, the 6mm ARC is offered in 103gr to 108gr.

The overall length of the rounds is the same at 2.26 inches.

Recoil

From looking at the rounds, you could guess they have very similar recoil.

Felt recoil depends on many factors, including the gun's weight, bullet weight, and shooter.

Neither round is known for high felt recoil, but the 6mm ARC doesn't pack as much punch as the 6.5 Grendel, which has 9-foot-pounds of recoil due to the lower case capacity.

This is because it holds slightly less powder and fires smaller projectiles.

The 6mm ARC has a slight advantage for recoil and is an excellent choice to introduce individuals to firearms apprehensive of guns because of recoil concerns.

Trajectory

The trajectory is the bullet's path to the target.

As shooters, we prefer a flat-shooting round over ammunition that requires us to adjust for bullet drop.

That's why 6mm bullets are so popular amongst medium-range to long-range shooters. They're known to be flat-shooting bullets.

The 6mm ARC is a more aerodynamic bullet than the 6.5 Grendel. At 400 yards, it has an average bullet drop of 22.2 inches.

The bullet drop for the 6.5 Grendel is slightly greater because it's a larger bullet. However, 25.3 inches of drop at 400yds is by no means terrible.

Therefore, the 6mm ARC has a flatter trajectory by 3.1" at 400yds.

The bullet drop difference will be exponentially more significant as we extend the distance. However, both rounds are excellent long-range rounds.

By a narrow margin, the winner is the 6mm ARC.

Accuracy

Accuracy is defined as how close the bullet hits the target compared to where the shooter aims.

While the bullet does affect accuracy, it also largely depends on the shooter, rifle, barrel length, and optics.

The 6mm ARC and 6.5 Grendel calibers are so similar that I seriously doubt you'll see a difference in accuracy if you're using comparable rounds, rifles, and optics, meaning the same brand of powder, guns, and optics, similar bullet weights, and projectile types.

This category is a tie.

Since it will vary depending on the shooter, some people are more accurate with a lighter recoil firearm, while others aren't as bothered by the recoil and can be as accurate with both.

Ballistic Coefficient

The ballistic coefficient (BC) measures how well a bullet resists wind drift and air resistance.

Put another way; it’s a numerical representation of the aerodynamics of the bullet.

A high BC is preferred since it means the bullet will resist the wind more.

Generally, a heavier grain bullet will have a higher ballistic coefficient as it takes greater force to disrupt a heavier bullet than a lighter projectile.

The ballistic coefficient varies from bullet to bullet based on design (aerodynamics), weight, and other factors.

We would assume the 6.5 Grendel has a higher BC since it tends to have heavier bullets; however, the 6mm ARC typically has a higher ballistic coefficient because of its greater velocity and more aerodynamic bullet.

A 123gr 6.5 Grendel hunting cartridge has a BC of .510, while the factory ammunition 103gr 6mm ARC hunting cartridge has a BC of .512.

If we increase the weight of the 6mm ARC to 108gr eld match, the BC will increase to .536, while the BC will lower to .506 when we switch to a 123gr 6.5 Grendel match cartridge.

The winner is clear; the more aerodynamic 6mm ARC has a higher ballistic coefficient despite having lighter bullets.

Stopping Power/Sectional Density

Stopping power can be spoken of in terms of Sectional Density (SD), the measure of bullet penetration.

Stopping power is crucial when hunting big-game and medium-sized game since you'll need a bullet that can punch through thick hide, bone, and sinew to make a quick ethical harvest.

Sectional density is calculated by comparing the bullet weight and the bullet diameter.

The higher the SD, the deeper the bullet will penetrate the target.

This is a simplified view of penetration as there are other factors to consider, such as bullet expansion and velocity.

For this comparison to truly be accurate, we should use bullets that weigh the same. We can't, but we have the information that will give you a fair idea.

A 6.5 Grendel 123 gr Hornady hunting round has a sectional density of .252, whereas a 6mm ARC 103 gr hunting round has an SD of .249, which is only slightly less.

However, a 6mm ARC 108 gr match round has an SD of .261.

As expected, the sectional density ultimately comes down to bullet selection and velocity.

The higher velocity of the 6mm ARC means it will tend to have a higher SD. The SD is virtually the same when comparing similar rounds and isn't a significant concern for the average shooter.

Hunting

While the 6.5 Grendel and 6mm ARC are similar, hunting is where you'll see one of the most remarkable differences between the two rounds.

The lighter bullets of the 6mm ARC make it an ideal cartridge for varmints and predators like coyotes because it's decently fast and flat, shooting at long distances. It's also capable of taking deer and other medium-game.

However, it's not recommended to hunt a larger animal than a deer at any considerable distance with the 6mm ARC because it doesn't have the necessary bullet weight to make an ethical kill.

Within 100 yards, it could take down an elk or wild hog at close range, but if it were me, I would prefer to hunt anything larger than a deer with the 6.5 Grendel.

The 6.5 Grendel has more options for heavier bullets which pack a better punch for big-game hunting but are overkill when hunting varmints.

When choosing between these calibers for hunting, it's determined by the size of the animal you plan to hunt.

The 6.5 Grendel is best for medium and large game animals like deer, elk, moose, bear, and caribou.

The 6mm ARC shines best when hunting varmints like prairie dogs, groundhogs, and coyotes.

Home Defense

For self-defense when venturing through bear country, the 6.5 Grendel should be your go-to instead of the 6mm ARC.

However, I don't recommend either round for home defense and self-defense in an urban area.

Both calibers are intended as rifle ammunition, and rifles are not the best Everyday Carry (EDC) weapon, especially concealed carry.

These calibers are also too likely to penetrate walls and strike innocent bystanders.

Instead, a pistol chambered in .45 ACP or 9mm is an excellent EDC weapon, and a 12 gauge or 20 gauge shotgun is much better for home defense situations.

For an SHTF scenario, either caliber would be ideal because they are designed for the versatile AR-15 platform.

This means you can easily carry lots of ammo in easy-to-access magazines and quickly and accurately send rounds down range when needed.

This category is also a tie.

Ammo and Rifle Cost and Availability

Cost and availability is the greatest difference between these calibers.

The 6mm ARC is still a new caliber, so finding a rifle and ammo chambered in it isn't easy because only a few manufacturers make either. This also drives the price of both ammo and rifle up.

A quality rifle chambered in 6mm ARC will cost you about $1,400.

The cheapest 6mm ARC ammo will cost about $1.30 per round.

The 6.5 Grendel has been around for nearly two decades and is still gaining popularity, so ammo and rifles are much more abundant than the 6mm ARC.

It still doesn't compare in popularity to the 223/5.56, though.

A quality AR-15 chambered in 6.5 Grendel will cost you $600+. Bolt action rifles are also chambered in 6.5 Grendel, so if you prefer a bolt gun over an AR-15, then the 6.5 Grendel should be your choice.



The cheap 6.5 Grendel ammo will still cost $1.00 per round.



Based solely on the availability and cost of the guns and ammo, the 6.5 Grendel separates itself from the 6mm ARC.

As more manufacturers begin to make the 6mm ARC, the availability should go up, and the price should go down, but for now, the 6.5 Grendel easily wins this category.

Reloading

Reloading is an excellent way of controlling controllable variables. You can craft the ammo that your rifle cycles the best, unlike with factory loads.

It's also a way to save a little money on factory ammo if you're willing to put in the time it takes to handload correctly.

If you enjoy reloading, then either of these calibers will be an excellent choice. However, since the 6ARC is still a new round, it will be more challenging to find all the supplies you need to reload it.

Bullets for the 6.5 Grendel are becoming more common because the 6.5 Creedmoor is also gaining in popularity to reload, and they use the same bullets.

Finding reloading supplies such as brass, primers, bullets, and powder for the 6.5 Grendel will be easier than finding some of them for the 6 mm ARC.

A Brief 6mm ARC Development History

The 6mm Advanced Rifle Cartridge (ARC) is a newly developed round by Hornady. They wanted to create a round that could compete with the popular 223/5.56 in an AR-15, but it needed to shoot flatter at longer distances.

In 2020, Hornady released the 6mm ARC, and so far, it's lived up to the hype.

It's based on the .220 Russian, like the 6.5 Grendel, which is why they're such similar rounds.

A Brief 6.5 Grendel Development History

The 6.5 Grendel case has become a favorite of AR-15 shooters in the last couple of decades.

Released in 2003, it gained approval from Sporting Arms and Ammunition Manufacturer's Institute (SAAMI) in 2011.

In the last decade, it has gained a loyal following. So much so that some shooters don't believe the 6mm ARC can take enough of the market from the 6.5 Grendal to remain viable.

Who told those guys you couldn't enjoy both?

Are you curious how the 6.5 Grendel vs 308 debate turned out?

Final Shots: 6.5 Grendel vs 6mm ARC

When it comes to the 6mm ARC vs 6.5 Grendel, minute differences make each one stand out in certain circumstances.

The 6mm ARC is your best option if you're long-range target shooting and only occasionally go deer hunting because it shoots much flatter than the 6.5 Grendel.

However, if you're a big-game hunter, the 6.5 Grendel will perform better because it has a little more knockdown power due to the larger bullets.

In a perfect world, you could buy an upper for each caliber. If that's not feasible, the 6.5 Grendel is the better all-around caliber because of its versatility.

6mm ARC vs 6.5 Grendel: Which AR-15 Round Is Best? originally appeared on Ammo.com
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Old 07-07-2022, 02:48 PM
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There is a ridiculous amount of misinformation and false statements being made in this article:

Originally Posted by ammodotcom
The rim diameter is even closer with only 0.001 inches difference—the 6.5 Grendel is 0.44 inches in diameter, whereas the 6mm ARC is 0.441 inches in diameter.
This is incorrect. Both the 6.5 Grendel and 6mm ARC use the exact same 0.441 - 0.010" rim diameter specification. Reference SAAMI drawings before penning your articles.

Originally Posted by ammodotcom
The 6.5 Grendel has a broader range of bullet weights, ranging from 90 grains to 130 grains. In contrast, the 6mm ARC is offered in 103gr to 108gr.
Load data is available for the 6 ARC ranging from 55/58grn up to 110grn, and some guys are already loading 112 Match Burners and 115 DTACs.

Originally Posted by ammodotcom
The 6mm ARC has a slight advantage for recoil and is an excellent choice to introduce individuals to firearms apprehensive of guns because of recoil concerns.
This might be worse than counting the number of angels dancing on the head of a pin... 28.5grn 8208 pushes a 123 ELD to 2550 in the 6.5 Grendel, while 28grn 8208 pushes a 108 ELD to 2700 in the ARC... This puts the two within 4% for recoil momentum... 4%... That's not an appreciable difference in recoil.

Originally Posted by ammodotcom
The bullet drop difference will be exponentially more significant as we extend the distance. However, both rounds are excellent long-range rounds.

By a narrow margin, the winner is the 6mm ARC.
For Long Range shooting, transonic transition matters, and the "narrow margin" isn't so narrow here. The 6 ARC will hold onto super-sonic speeds with 105 Hybrids, above the transonic boundary, clear out to 1250yrds, while the 6.5 Grendel falls short, dropping transonic at only 975yrds. This means the Grendel gets a smack in the tail by its pressure wave before it even reaches 1000yrds, and groups get squirrelly, almost 300yrds earlier than the ARC... That's around 30% transonic range advantage... Acknowledging here also, the ARC has around 10moa/3mils less drop at 1000yrds, and a quarter second shorter time of flight and HALF of the wind drift at 1000 (2.1MOA vs. 3.9MOA for the Grendel)

Originally Posted by ammodotcom
the 6mm ARC typically has a higher ballistic coefficient because of its greater velocity and more aerodynamic bullet.
Ballistic Coefficient is a measure of aerodynamics. It's redundant to say the ARC has a higher BC because of more aerodynamic bullets - that's how bullet aerodynamics are defined... It's like saying taller people are taller...

Ballistic Coefficient is NOT dependent upon velocity, so the first half of this sentence is just poorly representing relatively simple science.

Originally Posted by ammodotcom
the sectional density ultimately comes down to bullet selection and velocity.

The higher velocity of the 6mm ARC means it will tend to have a higher SD.
This statement is completely false, again misrepresenting simple science. Sectional Density is calculated by bullet weight in pounds divided by bullet diameter squared, and has absolutely no dependence upon velocity. SD is ONLY dependent upon bullet weight and caliber.

Originally Posted by ammodotcom
The 6.5 Grendel is best for medium and large game animals like deer, elk, moose, bear, and caribou.

The 6mm ARC shines best when hunting varmints like prairie dogs, groundhogs, and coyotes.
Both of these claims are steeped in idiocy. Recommending the 6.5 Grendel for Elk, Moose, caribou, and bear while relegating the ARC to coyotes and varmints is just dumb, and illustrates a complete lack of experience by the author with either of these cartridges, or ANY cartridge used for hunting these animals. This is akin to saying a 12oz framing hammer is only suitable for tapping finish nails into trim, while a 14oz framing hammer is suitable for crushing boulders...

Originally Posted by ammodotcom
A quality rifle chambered in 6mm ARC will cost you about $1,400.

A quality AR-15 chambered in 6.5 Grendel will cost you $600+.
These claims also are false. Equivalent models from manufacturers which offer both are priced the same. Savage is offering both the 110 Tactical and Axis II in 6 ARC, under $900 and under $500 respectively, Howa is offering the 1500 Mini action in 6 ARC as well for $1100.

Originally Posted by ammodotcom
Bullets for the 6.5 Grendel are becoming more common because the 6.5 Creedmoor is also gaining in popularity to reload, and they use the same bullets.
This is more of the author's inexperience showing through. Guys are shooting 140-147grn class bullets typically in 6.5 Creedmoor, while the tiny 6.5 Grendel case and AR-15 Mag lengths tap out in the 125-130 class bullets for the Grendel.

Originally Posted by ammodotcom
Finding reloading supplies such as brass, primers, bullets, and powder for the 6.5 Grendel will be easier than finding some of them for the 6 mm ARC.
Lots of false on this as well. Primers and powder are exactly the same for the Grendel and the ARC, so if you find one, you've found the other. ARC brass can be made from Grendel brass in a pinch (or from 7.62x39 for either of them). Further, 6mm bullets typically are more easy to find than 120-130grn class 6.5mm bullets. So again, the author is making claims out of inexperience and ignorance.

Originally Posted by ammodotcom
A Brief 6mm ARC Development History


So... um... Why would you not acknowledge the actual development history? Did you completely miss the marketing and solicitation award announcements which described the origin of the 6 ARC as a DoD solicitation?

Originally Posted by ammodotcom
A Brief 6.5 Grendel Development History


Equally as disappointing as the failure to actually describe the 6 ARC's development history is the author's failure here to describe the 6.5 Grendel's history. How can the author even write a "development history" of the 6.5 Grendel without even typing the words "Bill Alexander" or "Alexander Arms"? How can they ignore the 8 years of name game that Wild Bill played which forced so many of us rifle builders and shooters to buy "264 LBC" dies and barrels (Les Baer Custom) until Bill Alexander FINALLY released his trademark of the Grendel name, allowing SAAMI standardization and broad market opportunity...? How can they write a section on “development history” of the 6.5 Grendel and not acknowledge Type I and Type II boltheads, and Black Hole Weaponry’s influence on these in the market?

Both of those "brief development history" sections are exceptionally half-assed.

Originally Posted by ammodotcom
However, if you're a big-game hunter, the 6.5 Grendel will perform better because it has a little more knockdown power due to the larger bullets.
More inexperience being rolled up into misrepresentations here... The 6 ARC has greater impact momentum, greater penetration from improved sectional density, greater impact energy, and greater impact velocity for reliable expansion at common hunting distances. Neither are a good choice for true big game hunting, but for deer sized CXP2 game, the ARC does anything the 6.5 Grendel does, and does it farther away.

You guys need to hire a content editor which actually knows something about any of these things, because your articles are consistently dumpster fires.

Last edited by Nomercy448; 07-08-2022 at 03:30 AM.
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Old 07-08-2022, 01:53 AM
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I don't think the author has enough work to do. He keeps posting verbose answers to questions no one is asking.
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Old 07-08-2022, 03:27 AM
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Originally Posted by Wingbone
I don't think the author has enough work to do. He keeps posting verbose answers to questions no one is asking.
They’re an ammo website which run a podcast and spam forums like this all over the place to advertise for their business.

If they had the appropriate knowledge and experience to be giving the advice they give, or at least did any modicum of proper research to develop their articles so they wouldn’t be so riddled with inaccuracies, I’d be more forgiving of their thinly veiled advertising they do. But it is obvious in most of their posts that they don’t even take the time to read a Wikipedia entry as research, and don’t really care if their copy holds any accuracy or truth - they just want to spin their name out there to advertise their ammo sales website.
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Old 07-08-2022, 07:28 AM
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Originally Posted by Nomercy448
They’re an ammo website which run a podcast and spam forums like this all over the place to advertise for their business.

If they had the appropriate knowledge and experience to be giving the advice they give, or at least did any modicum of proper research to develop their articles so they wouldn’t be so riddled with inaccuracies, I’d be more forgiving of their thinly veiled advertising they do. But it is obvious in most of their posts that they don’t even take the time to read a Wikipedia entry as research, and don’t really care if their copy holds any accuracy or truth - they just want to spin their name out there to advertise their ammo sales website.
Even worse
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Old 07-11-2022, 06:22 AM
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they just want to spin their name out there to advertise their ammo sales website.
Correct I dont even see them listed as a HNI sponsor yet they are allowed to advertise here. Funny too because just a link to New Ultra Light Arms in my sig was removed because they felt i was "advertising".
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