Hornady Refines Its Monometal Bullet Design

As Hornady’s Seth Swerczek stated to me, “All bullets are tied to velocity for their performance and none more than a monolithic.” The company was about to introduce a refined, updated version of its excellent monometal GMX bullet, and I was getting the lowdown. Long, low-drag versions featuring Doppler radar-tested and refined aerodynamics and best-possible accuracy were Hornady’s goal.

Let’s dive right into why this is a big deal.

Monometal bullets have very real performance advantages and, in areas restricted to so-called “non-toxic” projectiles, a legal advantage, too. However, monometal projectiles are also handicapped by the very material of which they’re made.

Because copper and copper alloys have less inherent density than lead, monometal bullets made entirely of a copper/copper alloy cannot have the same level of ballistic coefficient (BC) that lead-core bullets of similar size and shape have.

Multiple factors are at play. First, for a given weight projectile, monometal bullets have more surface area causing friction with air molecules. Second, the extremely heavy lead core provides momentum that can be shaped and shifted to enhance balance and stability. Third, modern monometal bullets usually feature one or more grooves around the circumference of the bullet, and those grooves cause additional friction.

Nothing can be done about the material density or surface area, but why not get rid of the grooves? Because the benefits outweigh the downsides.

Monometal bullets are not nearly as malleable as lead-core bullets, and the grooves allow rifling to engrave into the bullet more easily by reducing the amount of material that must be displaced and the amount of bullet-on-bore bearing surface. This results in reduced pressure, which in turn allows zestier handloads that push the bullets faster. Faster, in most cases (particularly with most monometal bullets), is better.

Additionally, the grooves usually benefit accuracy.

Barnes Bullets first introduced grooves on its Triple-Shock bullet, and it proved to the world that monometal projectiles could be spectacularly accurate. Ever since, savvy bullet engineers have been working to determine the optimal shape and the minimum number of grooves necessary to keep pressure low and accuracy high, so as to minimize that drag the grooves inevitably apply.

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Hornady’s engineers have massaged both the material and the shape of the old GMX (Gilding Metal eXpanding) bullet. The result is the new CX. Its mother material is no longer the traditional 95/5 percent copper/zinc alloy. The actual composition is proprietary. Let’s just say this: If Hornady’s ballisticians saw fit to finesse performance by perfecting an alloy, you can count on it being a good thing.

Shape, too, has been computer modeled for maximum aerodynamics, using space-age feedback generated by extensive Doppler radar testing.

Just as important, Hornady introduced its space-age Heat Shield tip to the CX line. Initially designed for the extreme-range ELD Match (Extremely Low Drag Match) and ELD-X (eXpanding), the Heat Shield tip is made of a proprietary composite that is resistant to heat and erosion. The tip maintains its shape when traveling through the atmosphere at Mach III. That means its BC (or more accurately, its drag coefficient) stays the same, too, instead of degrading slightly (as polymer tips fired at extreme speeds do).

It’s also worth pointing out that copper and copper alloys are much less malleable than lead. The Heat Shield tips are engineered—using science far above my understanding—to initiate and optimize expansion. CX bullets feature a deep hollow cavity, enabling big, double-diameter mushrooms.

As a result of all these small refinements, the useful terminal performance window of Hornady’s monolithic bullet line has been enlarged. Most significantly, the CX’s ability to maintain velocity out at long range has been upgraded from the old GMX design, so bullets fired at the same muzzle velocity will impact way out there with higher velocity. Or considered another way, they’ll maintain minimum impact speed (2,000 fps minimum for reliable expansion) at distances greater than the GMX did.

The lineup itself has been broadened, too. It now includes projectiles optimized for modern long-range cartridges. They include a 130-grain CX with a long, sleek nose designed for the 6.5 Creedmoor and 6.5 PRC and a 190-grain CX, with a similarly racy profile, designed for the .300 PRC.

Certainly, the CX is gunning for the Barnes LRX bullet, which is the leading high-BC monometal bullet on the market, and for the boutique bullets from Hammer and Cutting Edge and all the others that boast above-par ballistic and terminal performance.

The “CX” name is for “Copper alloy eXpanding,” which makes sense. However, I also like to think of it as “Controlled eXpansion.” Without doubt, the CX is the toughest, deepest-penetrating, all-round hunting bullet in Hornady’s lineup.

Now, before moving into all the versions of the CX, it’s important to note that Hornady’s bullet design gurus are starkly aware of all the various pieces of performance that make up a well-balanced puzzle. The performance envelope has been pushed in every other worthy way, too. Accuracy has been finessed. Impact velocity expansion windows have been researched, tested, and optimized.

However, and this is an important “however,” when you’re unwilling to push a certain envelope, say, BC, past the point where it has a detrimental effect on a different envelope, say, accuracy, you may end up with a beautifully balanced bullet—but one whose specs don’t appear stunning on paper or in the ballistic apps on every armchair expert’s smartphone.

What I’m saying here is that in addition to the new super-sleek CX projectiles, such as that 130-grain 6.5mm and the 190-grain .30 cal., you’ll see CX bullets with rather ho-hum—but entirely honest—BCs. A good example is the 130-grain .277-caliber version, with its BC of .403. Another is the 110-grain .30-caliber version designed for the .300 Blackout, with a BC of just .312. Clearly, it’s not a long-range bullet, but rest assured, within its comfort zone, it’s a darned good terminal performer.

The CX Lineup

Hornady’s CX line starts with the 80-grain 6mm bullet and runs up through a 250-grain .375-caliber version. Most useful weights in most popular calibers within that spectrum are covered.

I say “most” because there is one hole: No heavy-for-caliber 7mm CX yet exists. Hornady isn’t willing to manufacture a bullet that won’t stabilize in 1:9.5 rifling twist rates (common in various 7mm cartridges) in freezing temps at sea level. The heaviest 7mm CX is 150 grains. It’s no slouch, but I write “yet” for a reason. I maintain hope that Hornady will eventually provide advanced shooters with a heavy 7mm CX to handload in their fast-twist rifles.

That said, I just can’t find fault with the rest of the CX lineup. Droning on about calibers and projectile weights is a sure way for readers to lose interest, so if you’d like to see more, check out the accompanying list.

On the Range

For this report, Hornady kindly sent me two boxes of early-production Outfitter factory ammo loaded with CX bullets. They included the 130-grain 6.5 PRC load and the 190-grain .300 PRC load.

Shooting the 6.5 PRC ammo in a Gunwerk’s ClymR rifle showed that while the 6.5 PRC factory load’s muzzle velocity is nothing to write home about, it is impressively accurate. The average of three consecutive three-shot groups fired from a benchrest at 100 yards was exactly 0.50 inch.

Fired from a Proof Research Glacier Ti rifle, the more potent .300 PRC ammo showed promise, with two of three bullets generally landing right next to one another. The average was 0.95 inch—still genuine sub-MOA accuracy, with factory ammo, in a very lightweight mountain rifle. I’ll take that any day.

Swerczek also sent samples of several other CX bullets, so I handloaded the 130-grainers for a custom 6.5 Creedmoor rifle, the 150-grainers for an AllTerra Arms rifle in 7mm Remington Magnum.

A pound of Alliant’s new Reloder TS 155 powder made a sensible pairing with the 6.5mm projectile. Because data is still scarce, I was tentative, so my test batch produced modest velocities. Accuracy, on the other hand, was anything but modest. Three consecutive three-shot groups fired without allowing the barrel to cool resulted in a 0.43-inch average. One group was a genuine one-holer, measuring just 0.14 inch.

I loaded the 7mm Rem. Mag. with Hodgdon H1000. Because the gun is a lightweight hunting rifle, unlike with the 6.5 Creedmoor, I allowed the barrel to cool between three-shot groups. The AllTerra rifle liked the 150-grain 7mm CX, averaging 0.59 inch.

Arguably the best of all the CX bullets—and notably the one with the highest BC—is the 190-grain .30-caliber version. My friend Bill Golightly, a mule deer savant and rifle-accuracy disciple, was kind enough to test them in his superbly accurate AllTerra Arms .300 PRC. Initial results averaged 0.74 inch at 100 yards—not what the rifle is capable of with its favorite load, but promising.

Interestingly, the CX bullets seemed to become more accurate in some rifles after several shots had been fired. Presumably, this is because consistency increased and stabilized as the bullet and propellant behind it laid down a layer of their particular flavor of fouling. It’s a phenomenon I’ve seen before but not as distinctly as with the CX.

One of the more notable cases was with a Browning rifle tested by my friend Colton Heward, who hunted deer on Kodiak Island with it (more on that in the next section). Initially, his rifle didn’t like CX bullets at all. Of course, the rifle was brand new, and the barrel needed a bit of break-in. At any rate, after a box or two of ammunition, groups began to tighten significantly. Colton told me his last seven shots at 100 yards were all easily sub-MOA. That’s plenty good for a production rifle loaded with factory ammunition.

In the Field

While I haven’t had the opportunity to hunt with the CX bullets, Colton and his father took three big Sitka blacktail bucks on Kodiak Island. All three were one-shot kills, and bullet performance was stellar. Each evening, after the day’s hunt, we’d swap hunting stories.

Colton’s first buck was shot while bedded from a fraction over 300 yards. The deer never got up. His second was a big “stag” buck, which is the name Kodiak locals use for a certain percentage of the blacktail bucks that never mature sexually. They grow antlers with massive bases, rarely shed their velvet, and sometimes go a couple of years without shedding their antlers. Rather than growing a fresh set of antlers in the springtime, some grow additional points around their existing antler bases. As a result, some of these bucks can be spectacular. Big ones are a prized novelty, and because they never rut, they tend to have bulky, fat bodies and are very tender eating.

Most Sitka blacktails are not particularly skittish. Some are. Old enough to be wise, Colton’s stag cottoned on that he was being stalked and became edgy. Still 521 yards away, Colton had to take the shot or lose the opportunity. His rifle was a Browning X-Bolt Max LR chambered in .300 PRC, loaded with 190-grain CX bullets—a comforting load in Kodiak bear country.

Lying prone, Colton dialed the custom CDS turret atop his Leupold VX-6HD scope, calculated wind drift, and took the buck cleanly with his first shot, dropping it in its tracks. Score two for the CX.

Later that day, Colton’s father, Gary, used the same rifle to take a heavy-horned, classic 3x3 blacktail with brow tines. His 230-yard shot was also a one-and-done proposition.

Hornady has made a point to support hunters equipped with calibers all the way from easy-shooting, zippy 6mms up to hard-walloping .375s. That’s a wonderful thing, particularly for hunters in lead-restricted areas.

Like any monometal projectile, CX bullets are likely to exit and leave good blood trails. Unlike lead-core bullets, they don’t cause huge-diameter wound cavities, and they don’t leave lead fragments in meat. Both characteristics should make venison lovers happy.

Instantaneous, bang-flop kills are less likely than with lead-core bullets, unless bone or nerve centers are hit. This is because of those different terminal performance characteristics. However, CX bullets will penetrate spectacularly, so they’re a top pick for angled and lengthwise shot presentations.

On principle, I disagree with lead-bullet restrictions, but the so-called “non-toxic” bullets available to hunters have become so darned good that in many cases, I choose to use them over traditional lead-core bullets. Hornady’s new CX is certainly one of the great ones. It’s accurate, aerodynamic, and extremely effective on game.