6.5 Grendel vs. 5.56 NATO

The 6.5 Grendel cartridge fits quite easily in the AR-15, and most agree that it provides better performance than 5.56 NATO. But is it worth the upgrade? Are there any downsides to using this faster, more powerful round? Might 5.56 NATO (and .223 Remington, for that matter) be a better choice for certain applications even still? We're comparing.

6.5 Grendel in a Nutshell

As an AR owner, you can think of 6.5 Grendel as a "fat" 5.56 NATO, or even a hyper-accurate version of an AR chambered with AK-47 loads. This 6.5x39mm cartridge sports a .224" bullet with a bunch of extra powder in the casing, providing velocities equal or similar to 5.56 NATO and .223 Remington (about 2,500 to 2,900 FPS) with a heavier bullet that provides a higher ballistic coefficient. That's fancy talk for a bullet with better wind resistance, a flatter trajectory, and thus more hit probability at longer distances.

What kind of distances are we talking? Most Grendel loads are capable of providing good accuracy up to 800 meters downrange. That's about double the accuracy of your typical 5.56/.223 load, and it manages all this while providing more muzzle energy and thus, more energy downrange, too. We'll get into the nitty-gritty of ballistics soon.

The "Unofficial" Grendel Clone

The Grendel cartridge is officially trademarked by its original manufacturer, Alexander Arms. That means any other ammunition developer or gun barrel maker who wants to build Grendel bullets or parts needs to pay a royalty to Alexander Arms. To get around this, some manufacturers took to building a knock-off, or clone, that is essentially identical while requiring a different extractor to avoid trademark infringement. This clone cartridge is called .264 LBC, or "Type 1 Grendel", while official ammo and parts are often labelled "Type 2 Grendel." This is merely an identifier made up by the original clone manufacturer, Black Hole Weaponry, to differentiate between the two.

What is 5.56 NATO?

Think of 5.56 NATO as a hot-loaded or "+P" version of .223 Remington. Although both cartridges use the same brass with identical measurements, 5.56 NATO barrels are cut with a 0.125" longer throat, (the area past the chamber which holds the bullet in front of the rifling) and the round develops more chamber pressure than .223 Remington, by about 3,000 PSI.

Physical Specs Compared

At first glance, these two cartridges don't appear so different. They maintain the same overall height, similar max pressures - 5.56 NATO reaches just 3,000 more PSI - and Grendel's bullet diameter is just 0.04" wider. Except Grendel's higher case capacity - which is about 22% greater - provides that extra velocity for its heavier bullets. Grendel maintains a base diameter of 0.439" compared to 5.56's 0.377", allowing for all that extra powder to burn. Of course, a longer barrel is required to achieve optimal velocity, so let's look at ballistic specs and compare further.

Ballistics Compared

Energy

There's little to be said here: 6.5 Grendel provides much more power and energy, especially downrange. Where 5.56 NATO is producing about as much energy as a lightweight 9mm cartridge at 500 yards, Grendel is still providing almost 900 lb.-ft. of energy.

Wind Drift

The competition isn't close here, either. The Grendel cartridge provides almost 50% less wind drift at 500 yards compared to 5.56 NATO's two most common 55-grain and 62-grain loads. It is only within 100 to 200 yards that all three cartridges remain comparable, here. Grendel quickly shows its advantage at 300 yards and beyond, where it only shifts about 7" compared to 5.56's 11.6" and 10.6" of drift, respectively.

Bullet Drop

It is here that 5.56 NATO shows its surprising ability to out-shoot 6.5 Grendel, although it's not by much. At 500 yards, 5.56 drops about 10% less, or approximately 5.1". Within 500 yards, all three loads - Grendel and both 5.56 loads - drop within 4.3" or less of each other.

Ballistic Coefficients

Ballistic coefficient, or BC, measures a rounds ability to overcome air resistance in flight. Obviously, Grendel has shown through its wind drift chart above that its BC is much higher than that of 5.56 NATO. Let's put the figures into, well, actual figures.

Grendel BCs

• Hornady 123-grain ELD: .506
• Alexander 123-grain HPBT: .527
• Federal 130-grain ELD: .530

5.56 NATO BCs

• Federal M193 FMJ: .267 BC
• Federal M855 Steel Core: .301

Overall, Grendel's BCs are nearly 50% greater, which correlates quite well with its nearly-50%-greater ability to resist wind drift downrange.

Max Effective Range

With all ballistic data considered, it's generally agreed upon that Grendel's max effective range is about 800 yards. Hunters can expect to reliably snag medium-size game at 400 to 500 yards with this cartridge. 

The U.S. Army says that the typical 5.56 NATO cartridge maintains a max effective range of 450 meters, but the cartridge only remains truly lethal at about 275 to 300 yards. Shooters who utilize match-grade barrels of 20" or more report the ability to hit targets at up to 600 yards, but bullet drop is so great (and energy is so low) that this is only practical for the challenge of long-distance shooting such a small, light round. Such a configuration would be ineffective for any sort of hunting.

Grendel v. 5.56: Other Comparisons

Barrel Length

It's not just performance that matters. The AR-15 your chamber your rounds in - specifically, the way that rifle is configured - is just as important. If you want a highly maneuverable weapon system but need a long, heavy barrel to obtain accuracy with your chosen cartridge, then what's the point? It's here that 5.56 NATO may still be the cartridge of choice for many AR owners. After all, range isn't everything.

6.5 Grendel

Thankfully, Bill Alexander (he's largely credited with developing 6.5 Grendel) gave a pretty clear-cut answer and says that 6.5 Grendel needs a barrel measuring 20" or more to provide all its power and accuracy at distance. 

5.56 NATO

Lucky for the AR platform, the 5.56 NATO is effectively optimized for velocity and accuracy with a 16" barrel. That happens to be the minimum legal barrel length for any rifle. By sticking with 5.56 over Grendel, you get to effectively shave off 4" of steel (and a lot of extra weight) from the business end of your AR-15.

Barrel Life

Normally, no AR-15 owner - no matter how often they hit the range - will shoot out a barrel, stripping it of rifling and accuracy. Except that fast, high-BC loads like 6.5 Grendel can provide a significantly shorter barrel life, resulting in just such a possibility for the average rifle owner.

Many AR-15s chambered in 5.56 NATO can survive on a single barrel for at least 12,000 to 15,000 rounds and still maintain MOA accuracy. High-end nitride and chrome-lined barrels can last for up to 20,000 rounds, and only then will an advanced shooter notice a loss in accuracy. 

Except when it comes to 6.5 Grendel, which requires maximum velocity to obtain accuracy, barrel life begins to degrade noticeably at 4,000 to 5,000 rounds. The problem isn't necessarily a loss of rifling. It's a loss of speed from the barrel suffering simple erosion and thus, lower pressure. 

Ammo Availability & Cost

5.56 NATO wins handily in the ammo department when it comes to availability and cost, too. The 6.5 Grendel is still considered a high-end "niche" cartridge, and fewer manufacturers produce it compared to the hundreds of manufacturers who pump out hundreds of millions of rounds of 5.56 NATO every year. At the time of this publication, you can find new-brass 5.56 for about $0.68 per round. Match-grade ammo can be found for about $1.25 per round. Just two years ago, you could grab the same ammo for as little as $0.35 per round.

That's not the case for Grendel. Right now, the cheapest rounds are at least $1.50 each, and that's for "basic" stuff. Match ammo, required for shooting to that mythical 800-yard mark, will run you a cool $3.00 to $4.50 per round. That's at least $70.00 for a simple 20-round box, not even enough to fill a single magazine. Ouch.

Receivers, Bolts, and Parts Kits

If you're still sold on Grendel, you'll be happy to know that it shares just about every major component with the 5.56 platform. The Grendel cartridge only requires a different bolt, extractor, barrel, and barrel extension. Everything else  - stripped upper and lower receivers, bolt carriers, lower parts kits, buffers, recoil springs, buffer tubes, gas systems and buttstocks - remain the same.

Recap

We've covered just about every point to consider in comparing 6.5 Grendel vs 5.56 NATO. Here's a quick list to commit the main points to memory:

• 6.5 Grendel utilizes 5.56 NATO parts, except for the bolt, barrel, and barrel extension
• Grendel maintains almost three times as much kinetic energy at 500 yards and beyond.
• Grendel provides about 50% less wind drift than 5.56, thanks to its high ballistic coefficient.
• 5.56 NATO beats 6.5 Grendel when it comes to bullet drop within 500 yards. It falls about 10% less.
• 5.56 NATO's max effective range is about 450 yards, although its only lethal up to 300 yards.
• 6.5 Grendel's max effective range is about 800 yards. It can be used to hunt up to 500 yards.