How Do Copper vs. Lead Bullets Affect Your Hunt?

Wherever rifle shooters gather, choice of bullets is a favorite for a campfire discussion. We all have our favorites. If you are 40-something, you grew up shooting lead-core jacketed bullets. This is because homogeneous-alloy expanding bullets didn’t exist until the mid-1980s. Today we have choices. Or at least some of us do. There are places like California where “unleaded” projectiles are mandated for all hunting.

Many hunters love copper-alloy bullets. Others damn them. We love our favorites, and we hate being told what we must shoot. Some prefer good old cup-and-core bullets. Others prefer bonded-core. Then there are polymer-tipped bullets, and let’s not leave out the dual-core bullets: Nosler Partition, Swift A-Frame, Federal Terminal Ascent.

Many bullets combine several of these designs, and let’s not forget the fairly new low-drag bullets, designed first and foremost for the highest ballistic coefficients possible. Bullet technology today is complex and varied, but from the early days of blackpowder until 1886, things were simple. Bullets were lead, perhaps hardened with a bit of antimony. There were advancements: from round lead balls to conical; to hollow-base (the Minie ball, to upset into the rifling); and light-for-caliber with a hollow nose to increase velocity (the British Express). All were bullets of homogeneous metal.

Smokeless powder velocity created a problem. Lead couldn’t be hardened enough to prevent stripping through the rifling. The jacketed bullet was a parallel development that enabled effective use of the new nitrocellulose propellant: a jacket of harder metal encasing the lead. Early jackets were often cupronickel, an alloy of copper and nickel and silver in color. Nickel is costly, but it makes sense, for military use because cupronickel resists saltwater corrosion and doesn’t tarnish.

Copper Bullets

Eventually, nicely malleable copper became the standard. For nearly a century, most bullets were cup and core, in which a drawn copper or mild alloy cup encases a lead core. Military bullets and non-expanding solids for the largest game had no exposed core at the tip because they were designed to hold together and penetrate. Jacketed hunting bullets were left open at the nose so that upon impact the core would flatten and expand. The jacket would peel back, and a larger wound channel would result. Simple cup-and-core bullets are always velocity sensitive, but bullet makers quickly learned that expansion could be somewhat controlled by the thickness of the jacket and the amount of exposed lead at the nose.

With cup-and-core bullets, it is possible for the core to squirt out of its containing jacket during upset, a phenomenon known as jacket/core separation. Mechanical features such as Remington’s Core-Lokt and Joyce Hornady’s InterLock mitigate this. However, the lead core is softer than the jacket. In the violence of expansion and penetration, some exposed lead will be wiped away, with the bullet becoming lighter until it comes to rest or exits. In the latter half of the 20th century, much effort went into developing lead-core expanding bullets that would expand, penetrate adequately and retain weight. Wilhelm Brenneke’s dual-core TUG bullet was probably the first premium hunting bullet.

It’s so little known in this country that we give primary credit to John Nosler’s Partition. It is also dual-core, with the front and rear cores separated by a wall of jacket metal. The Partition works. The front core expands, while the protected rear core continues to drive, almost acting like a mini-solid and often exiting. However, the reality is that weight loss during penetration is unavoidable. How much depends on the starting weight, impact velocity and what kind of resistance the bullet met. Cup-and-core bullets recovered from game are pretty good if they retain more than 50 percent of their original weight. Partitions do better, but 35 percent weight loss isn’t unusual.

Core bonding—chemically binding the lead core to the jacket—greatly reduces the amount of lead that can be wiped away. Developed by Bill Steigers, his Bitterroot Bonded Core was the first bonded-core hunting bullet. It was nearly hand-made and scarce. Jack Carter followed with his much more available Trophy Bonded Bear Claw bullet, which today is manufactured by Federal. Bonding is fairly common now. We have Hornady InterBond and DGX Bonded, Nosler AccuBond, Winchester Power-Max, Remington Core-Lokt Ultra, Federal Trophy Bonded Tip, Norma Bondstrike and more.

Core bonding is an extra step, complicating bullet manufacture and increasing cost, but it allows large upset while reducing weight loss. Depending on the bullet, its weight and impact velocity, core bonding takes a lead-core bullet to about 80 percent weight retention, sometimes more. Federal’s Fusion uses a different and less expensive process, but it’s also in that retention range. In my experience, Swift’s Scirocco and Federal’s Trophy Bonded Tip will hit 90 percent retention. The Swift A-Frame and Federal’s Terminal Ascent, both complex dual-core bullets, commonly do even better.

---

How important are jacket/core integrity and weight retention? To target shooters they are meaningless. Accuracy is all that matters. Varmint hunters also don’t care. They want frangible bullets that expand rapidly and shoot straight. Big game hunters care, because they must have penetration. They want expansion, but they also want weight retention to ensure penetration. Plus, we like to recover “pretty” bullets with classic mushrooms to show our buddies.

To some degree, we make too much of this. The late Chub Eastman, long at Nosler, used to field customer calls. The great old Nosler Partition is rarely pretty, with the front half often messy or missing. Regardless of appearance, if you recover a bullet from downed game, the bullet did its work. If a customer was calling to complain about the final form of a recovered bullet, Chub would often ask: “At what point in the animal’s death did the bullet fail?”

Cup-and-core boattails are notorious for jacket/core separation. I have often found expanded jackets and mushroomed cores separate but together under the hide on the far side. Separation occurred and isn’t ideal, but it must have happened at the end, as the bullet slowed and tumbled. Did it “fail”? I think not. Copper-alloy bullets started with non-expanding bullets for pachyderms. Unlike traditional solids with heavy copper jackets or steel-jacketed solids with lead core encased in mild steel overlain with copper, homogeneous alloy solids are true solids—as in, one piece of metal. I first saw bullets of turned brass in southern Africa. A poacher we intercepted had some of these bullets with a primitive reloading kit. He would recover them, pound them into rough round and shoot them again.

Turning brass bullets is slow and costly, but various alloys of copper allow conventional manufacturing. A-Square’s Monolithic Solid and Barnes’ Super Solid were early “solid solids.” Nosler’s Solid is one of the latest. Upon recovery, some of these bullets are so perfect they literally could be reloaded and used again. Drawbacks are few except that copper alloys are lighter than lead, so bullets of equal weight are longer, creating feeding issues in some actions. And a copper-alloy bullet is harder and less compressible than a lead-core one. This is not a problem with modern actions, but it could be with older doubles. These actions are not strong, and their barrels were made of mild steel, often with thin walls.

The copper-alloy bullet solved the problem. Randy Brooks of Barnes Bullets started experimenting with a copper-alloy bullet that would expand consistently, while still being one piece of metal, with no core that could separate.  The century-old hollowpoint was the answer. The nose cavity is surrounded by a skived or uniformly cut meplat. Upon impact, material drives into the cavity and the nose peels back in petals.

In the mid-1980s, Randy and Coni Brooks came to see us at Petersen Publishing. Randy had a bunch of newfangled copper bullets, upset in water. All exhibited four razor-sharp petals that had peeled back in a uniform pattern—with nearly 100 percent weight retention. Trading on his Super Solid, he proposed to call it Super Soft. But if you held one of these recovered copper-alloy bullets between thumb and forefinger and looked at it nose, you could see a definite pattern in how it peels back. The Barnes X Bullet was born.

The Barnes X series is still with us, but today there are numerous options from the major makers: Federal Trophy Copper, Hornady CX and MonoFlex, Lapua Naturalis, Norma Eco-Strike, Nosler E-Tip, Winchester Copper Impact and more. Expansion is controlled and limited by the depth and diameter of the cavity, and skiving varies, but 35 years later, all copper-alloy expanding bullets function pretty much the same. There have been refinements. Early on, we learned that the non-compressible copper-alloy bullet created a pressure spike as it entered the rifling—not generally a safety issue but often causing finicky accuracy.

Rapid copper fouling was also a frequent issue. At the time, Barnes was the only horse in the copper bullet race. It solved its own problem with driving bands around the base of the bullet, which reduced the pressure spike and the copper fouling. These bands vary in number, depth and size among manufacturers, but most copper bullets now feature them.

Today, many copper expanding bullets are tipped, and the tip works the same as it does in cup-and-core bullets. Expansion starts more rapidly as the tip is driven into the bullet, but width and depth of expansion is still limited by nose cavity and skiving. Tips have evolved, too. Hornady’s new CX (Copper Alloy eXpanding) is the first copper bullet to use the company’s Heat Shield tip, an advanced polymer that does not deform from friction/heat during bullet flight.

You won’t recover very many copper-alloy expanding bullets. Most will exit, especially on deer-size game. When you do recover one, it’s usually gorgeous. We hunters love this. About the only thing that can go wrong is a petal or petals breaking off. Otherwise, a copper bullet recovered from game will be in the high 90 percentile for retained weight. In February, I shot a mid-Asian ibex with one of the first CX bullets used on game. I took a strong quartering-to shot into the front of the on-shoulder. We recovered the bullet in the off-hip—plenty of straight-line penetration. Retained weight was more than 99 percent, as pretty much the only thing missing was the polymer tip.

So why wouldn’t we use such bullets all the time? Some folks do. I love them, too, but I don’t use them all the time because, regardless of their wonderful weight retention, they don’t expand as much as cup-and-core bullets or bonded-core bullets. On game, I want adequate penetration, but I suppose I generally fall on the side of “all energy expended within the animal” rather than expended on rocks and trees on the far side. But that depends on the game. On deer-size game, I am most likely to use a lead-core bullet—sometimes bonded, often not—because unless I’m using a marginal caliber, a bullet that’s very light for caliber or a bullet traveling at extreme velocity, a lead-core bullet will deliver adequate penetration and create a larger wound channel.

Larger game, requiring more penetration, is a different story. It seems to me, the bigger the animal, the better the copper bullets work. They’re great on elk and bear, and they’re awesome for buffalo. There’s an exception for the latter, though. When working big herds, as is common in coastal Mozambique, we avoid them because of the risk of over-penetration. Hunting our California hogs and blacktails, we are obligated to use lead-free bullets. They’re great for hogs but sometimes unimpressive on our small deer—just in and out, with small exit wounds. The cure is simple. I just borrow a page from African hunters and avoid the behind-the-shoulder lung shot we American hunters prefer. I shoot for the center of the shoulder. Copper-alloy bullets will penetrate, probably through both shoulders, and while a bit of meat is lost, tracking is greatly reduced.

Lead-Core Bullets

When it comes to accuracy, lead-core bullets shoot well and so do copper bullets. As with all bullets, some rifles shoot copper bullets marvelously, others don’t. Much effort has gone into making copper bullets as accurate and consistent as lead-core bullets. As a class, they are probably not as accurate as the best lead-core bullets in terms of benchrest and record-setting accuracy. As Hornady’s Neil Davies once commented: “There just isn’t as much you can tweak on a copper-alloy bullet.” In terms of hunting accuracy—or adequate accuracy for most of us—for most of our purposes, they are fine, and some rifles shoot them best. My Joe Balickie .270, built before such bullets existed, shoots 130-grain GMX and Barnes TSX better than anything else. A Savage 110 .30-06 produced half-inch groups with 180-grain original Barnes X Bullets and not with anything else I tried.

True, some rifles won’t shoot copper-alloy bullets, but that’s the case with any given bullet. You have to experiment and try various bullets and loads to see what works—especially if, by virtue of zip code, you are obligated to use lead-free bullets. Chances are, you’ll find a load that is at least accurate enough for your purposes. Last but certainly not least, there’s downrange performance. By design, copper bullets cannot expand as much as lead-core bullets. As range increases and velocity drops, expansion diminishes. That’s true of all bullets. This is always a problem at the extreme ranges some people are shooting today, but the copper-alloy bullets are probably not the best choices for extreme-range shooting at game.

Of course, this depends on what “extreme” means to you. With adequate starting velocity, copper-alloy bullets are just fine to 500 yards. At close range, copper bullets are less velocity-sensitive than their lead-core counterparts. At low velocity and/or great distance, there is some risk they will act like solids and fail to expand. This is true of any bullet, but it’s truer of copper-alloy bullets. Copper bullets also fall behind in today’s low-drag race to the highest possible ballistic coefficient. Since copper is lighter than lead, a copper-alloy bullet will be longer than a lead-core bullet of equal weight and similar shape. When bullets get too long, manufacturers run into cartridge overall-length specification problems.

As the latest copper-alloy bullet, Hornady’s CX has been aerodynamically tweaked about as much as possible. The 180-grain .308 CX mics 1.520 inches in length. The 200-grain ELD-X I’ve been shooting is 1.532 inches long. I can load the two to about the same overall length, with similar seating depth. The 180-grain .308 CX has a G1 BC of .469. Twenty years ago, that would have been considered spectacular, but the 200-grain .308 ELD-X has a G1 BC of .626. The 190-grain .308 CX, the heaviest available, has a G1 BC of .575. That is spectacular, but it can’t fly as flat as the 200-grain ELD-X. And because of overall length issues, I doubt we’ll see copper bullets that can compete head-to-head with today’s extra-heavy low-drag bullets.

That’s splitting hairs. Copper bullets fly plenty flat enough for the ranges most hunters actually shoot and perform wonderfully. If you have a choice, shoot ’em if you like ’em. If you don’t have a choice, just understand how they work and why they’re different from our traditional lead-core bullets. Either way, you can use them with confidence—but not always with the exact same shots you’d consider for cup-and-core bullets.