The following review was accessed at: http://www.rmef.org/Hunting/RifleCart/Rifles/CopperBullets.htm on 8/15/2012.

Copper , Ballistically by Wayne van Zwoll

Lead-free bullets have been around for decades. Now they’re the rage. But how do they perform?

For bullets, lead is logical. It is dense, malleable and relatively cheap. When a hollow-base upstaged the patched round ball in the 1840s, the physical properties of lead were essential to its success. The pressure of powder gas in the base cavity expanded it upon firing, for a tight bore fit and good accuracy. Lubricated with mutton fat or beeswax, the Minie ball, was issued to Union troops for their Enfields during our Civil War.

After metallic cartridges and breech-loading rifles appeared, an expanding bullet base was no longer needed. In the 1890s, repeating rifles by John Browning and Paul Mauser put muzzleloaders on the skids. High-energy smokeless propellants supplanted black powder, hiking bullet velocities. Increased bore friction deformed traditional lead bullets, however, and accuracy fell off. Solution: a jacket to insulate the lead.

The .30-06 cartridge was conceived in 1900, when engineers at Springfield Armory began work on a battle rifle to replace the .30-40 Krag-

Jorgensen. The Model 1903 Springfield fired a 30-caliber rimless round with a 220-grain bullet at 2,300 fps that closely matched the 8x57 Mauser and its 236-grain bullet at 2,125. A year later Germany switched to a 154-grain 8mm at 2,800 fps. The Americans countered with the Ball Cartridge, Caliber .30, Model 1906, hurling a 150-grain bullet at 2,700. The first .30-06 bullets were jacketed with an alloy of 85 percent copper, 15 percent nickel. It did not hold up at .30-06 velocities. Fouling rendered rifles inaccurate. Tin plating reduced fouling, but over time, tin “cold-soldered” to case mouths and could cause pressure spikes. An alloy of zinc and copper, 5-95 or 10-90, solved the problem. It was known as gilding metal.

Gilding metal has protected lead cores at velocities far exceeding 4,000 fps. Properly married to uniform and concentric lead cores, it helps ensure fine accuracy and reliable expansion in big game. Over the last century, jacketed bullets have become ever more sophisticated. New materials, profiles and internal designs have followed the simple softpoints and hollowpoints that killed all manner of game before World War

II. Partitions, metal inserts and core-jacket bonding processes arrived to control expansion as big game bullets sped ever faster from the muzzle. Polymer tips hiked ballistic coefficients and helped initiate upset.

Then, in 1981, after the best lead-core bullets failed to pass muster on a hunting trip, Randy Brooks hatched the idea of a bullet made of pure copper. Others had toyed with this idea; but no one had brought a viable product to market. While still manufacturing Barnes lead-core bullets, Randy shifted the firm’s focus to solid-copper hollowpoints. Soon the Barnes X became as well-known among hunters as Nosler’s famous Partition, the dual-core big game bullet dating to 1947.

The X-Bullet drove deep, though its petals didn’t open as broadly as those on traditional lead-core bullets. Coated X-Bullets followed, the blue film reducing bore friction and copper fouling—both liabilities endemic to solid-copper bullets. Then came Barnes Triple Shock (TSX) bullets, with four circumferential grooves to reduce bearing surface and give shank material a place to move under land pressure. The Triple Shock soon became known for its deadly terminal performance and for more consistent accuracy than the X-Bullet. The recent addition of a polymer tip gave the TSX a higher ballistic coefficient. Now this bullet has a rival: Barnes’s own MRX. Its nose section is all copper, a hollowpoint with a polymer tip. It has the TSX profile, with shank grooves. But inside the copper envelope of the shank, you’ll find what Barnes calls a “tungsten-based Silvex” core. Extending from just behind the ogive to the heel, it adds heft without lead.

Now other bullet makers have introduced hunting bullets of copper or gilding metal construction, arguably in response to a lead-bullet ban in southern California condor range. Winchester, Remington, Nosler and Hornady plan to increase their lead-free bullet offerings. firms will surely add to their lead-free loads. There’s even a lead-free .22 WMR round from CCI (TNT Green).

Are jacketed lead bullets on their way out? How do copper bullets compare ballistically with lead-core bullets? Are they as accurate? What about their versatility—do they perform across a wide range of terminal velocities. Do they kill thin-skinned game as quickly?

First, a clarification: “solid copper” is commonly used to describe these bullets. They are not solid in the sense that non-expanding bullets are solids. They’re designed to mushroom. A hollow cavity ruptures the nose, enabling pre-scored petals to peel back, increasing diameter and destruction. Here “solid” refers to the bullet’s composition: either solid (“pure”) copper or gilding metal—copper/zinc alloy.

“Give up lead, and you give up speed in certain cartridges,” says Hornady’s chief engineer Dave Emary. “Cases designed for full-capacity charges behind heavy bullets don’t do quite as well with copper or gilding metal bullets, because to make weight, so to speak, these bullets must be longer than lead-core bullets. You have to put that extra length somewhere. Seating a bullet deeper reduces case capacity. Seating it to greater overall length can jam it in the magazine or throat. Any copper bullet with the dimensions of a lead-core bullet will be lighter. It won’t retain its velocity as well or carry quite as much energy.

Yes, you can start light bullets faster. “But a little more speed at the muzzle won’t offset a higher ballistic coefficient downrange,” says Dave. “And because copper is harder than lead, and gilding metal harder still, you can’t accelerate a lightweight non-lead bullet as fast as a traditional softpoint without boosting pressure. There’s too much friction from that hard shank.” He adds that cartridges like the .30-06 are more forgiving of long bullets than are most magnums. In single-shot rifles, throat dimensions can determine overall length, which may be greater than that permitted by a box magazine. “So you may be able to seat non-lead bullets out far enough to match lead bullets ballistically in dropping-block rifles with long throats.”

Another concern that attends copper and gilding metal bullets is throat life. Actually, most hunters needn’t worry. While harder bullet material hikes friction and accelerates wear, few riflemen shoot enough to ruin a throat with these bullets. And competitive shooters have so far stayed true to lead-core bullets.

Dave tells me that solid copper hunting bullets incorporate compromises in the nose. “You want an aerodynamic ogive, a pointed profile. But the small nose cavity in bullets of this shape doesn’t initiate upset at low impact speeds. We can make the cavity bigger—but only at the expense of ballistic coefficient. An open nose also tends to shatter when driven fast into tough targets. Copper bullets expand satisfactorily in a relatively narrow velocity window. We can make lead-core bullets that penetrate well when striking an elk at 3,000 fps but still open reliably in deer at speeds as low as 1,600. It’s difficult to make a copper bullet expand at less than 2,000 fps unless you make the cavity so big that the front end disintegrates when it strikes bone or heavy muscle at 3,000.” Small-diameter bullets— 25 caliber and under—pose a challenge in nose design, because there’s so little material forward of the shank. A slender nose limits options for cavity diameter.

“Lead-core bullets deliver better upset at long range,” Dave declares. But this, too, may affect few hunters. Most cartridges produce lethal mushrooms with either bullet type to 400 yards. That’s a very long shot. And the magnum rifles popular for long shooting keep velocities at sure-upset levels well beyond that.

As for penetration, the copper bullet does just fine, typically retaining more of its original weight than lead bullets and delivering a more symmetrical blossom, which tends to drive straighter. On average, petals on copper rifle bullets don’t gape quite as widely as jackets on lead bullets, assisted by the smashed core. But while double-diameter upset of a fast lead bullet opens a huge cavity in the vitals, damage caused by a copper bullet 1½ times its original diameter can be stunning, and penetration deeper. Not long ago I shot a couple of Australian buffalo with Barnes TSX bullets. Both drove to the off-shoulder. Both ruined tissue well outside the bullet channels. One hit the front knuckle of the off-shoulder so hard that it shattered the wrist-thick bone at mid-section, inches from point of impact. I couldn’t imagine any lead-core bullet dealing a more destructive blow.

Accuracy, too, can be on par with that of jacketed bullets. I’ve shot tight groups with TSXs, and Dave Emary tells me tests with the new

Hornady GMX bullet show it to be the equal of any in the firm’s lead-core line. Like the TSX, it has circumferential grooves. “We settled on two of standard .045 cannelure width,” says Dave. “In tests, they proved significantly better than one; with three we gained no perceptible advantage. The grooves reduce full-diameter shank surface by about 20 percent and give the shank material room to move under land pressure.” Dave explains that Hornady chose gilding metal (5 percent zinc) over pure copper because it’s less prone to copper fouling. He concedes that it’s also more brittle. “A lot of work goes into petal design to prevent breakage.”

Bob and John Nosler know about the challenges of making effective copper bullets. The E-Tip bullet showed up first in Winchester ammunition. Now Nosler hawks 150- and 180-grain 30-caliber E-Tips as components. “This bullet is all gilding metal,” explains Bob, “95 percent copper, 5 percent zinc. We call it 210 alloy. It has great tensile strength. E-Tips don’t foul barrels as readily as copper bullets. A deep expansion cavity ensures upset in light game.” That cavity is capped by a polymer tip for a high ballistic coefficient. It helps trigger expansion. The Nosler/Winchester E-Tip bullet features a tapered heel, or boat-tail. There are no circumferential grooves. E-Tips loaded by Winchester have the firm’s familiar black Lubalox coating.

The E-Tip owes much to Glen Weeks, Winchester’s centerfire ammo guru, who collaborated with the Nosler crew to deliver this bullet at record pace. Work began in October 2006, and prototype bullets appeared at the April 2007 NRA convention. “E-Tip’s metal is as hard as, or slightly harder than, copper,” says Glen, “so it has less tendency to gall. That means easier bore cleaning and reduced metal fouling.”

But what about sealing in the bore? To cork powder gas and ensure that the lands take an authoritative bite, bullets must be malleable. Lead-core bullets “slug up” nicely to fill the grooves. Not so copper and gilding metal. I asked Glen about the bullet’s accuracy and the pressure issue some companies have addressed with shank grooves.

“The secret to E-Tip’s fine accuracy is its deep nose cavity,” Glen says. “It extends well below the tip, down even below the ogive. So the leading portion of the shank can yield slightly as the rifling begins to engrave. Gas pressure on the bullet base clinches the deal, ensuring that E-Tip is securely gripped and seals the bore.” The cavity also moves center of gravity back toward E-Tip’s tapered heel. Better accuracy results. As for terminal performance, E-Tip delivers four-petal upset. But unlike some solid-copper bullets, E-Tip winds up with a broad face resembling that of a traditional softpoint. “It won’t drive quite as deep as the AccuBond,” adds Glen. E-Tip behaves more like the XP3, Winchester’s most recent lead-core bullet—one hailed for its versatility. The company loads 180-grain E-Tips to standard lead-bullet velocities: 2,620 fps for the .308, 2,750 for the .30-06, 3,010 for the .300 WSM and 2,950 for the .300 Winchester Magnum.

Remington announced a lead-free big game bullet last summer, in a Premier Copper Solid line of hunting ammunition. The polymer-tipped spitzer bullets have two shank grooves and tapered heels and are cataloged as solid copper. “They’re designed to expand reliably over a wide range of impact velocities,” says Eddie Stevenson, the company’s press contact and a dedicated hunter who knows as much about Remington ammo as anyone. “Our goal was double-diameter upset, with 98-percent weight retention in tough game. We’re right on target.” Remington’s 2009 ammunition offerings are slated to include half a dozen cartridges with Copper Solid bullets from .243 to .300 Winchester Magnum. In addition, Big Green catalogs .223 and .22-250 ammo with 45-grain lead-free bullets at 3,550 and 4,000 fps. “Their jacketed iron cores come apart violently on impact,” says Eddie Stevenson. “We call them our Disintegrator loads.” Frangible lead-free bullets from Barnes for smaller game had already shattered the popular illusion that lead is necessary if you want an explosive upset.

Randy Brooks is pleased with the reputation his X-Bullet and TSX have earned for deep penetration and high weight retention in tough game.

But he’s quick to point out that solid-copper bullets for deer-size animals deliver the accuracy and broad wound channels hunters have come to expect of lead-core softpoints.

“Our hunting bullets aren’t just for Volkswagen-size moose and bears. They’re versatile. Match the bullet to the game, and you’ll find them ideal for pronghorns and whitetails as well as for heavy animals with thick hides and big bones.” He adds that solid-copper Expander MX hollowpoint muzzleloading bullets have performed superbly in deer-size game at modest impact speeds. Other makers can claim similar results from their big-mouthed copper bullets in shotgun and black powder sabots.

What about other non-lead materials? Well, tungsten is denser than lead and performs successfully in shotshells. But it’s frightfully expensive—several times the price of lead. “We considered tungsten for Dangerous Game solids,” Dave tells me. “But our jacketed lead-core bullets work as well and cost less.” Those solids wear laminated jackets, copper sandwiching steel. “So we get the strength of steel with the surface properties of copper.” A solid bullet for elephants could, of course, be made of copper or gilding metal. But sectional density matters a great deal when the bullet must drive through massive bones.

Of major U.S. bullet companies, only Sierra and Swift have yet to list a lead-free centerfire bullet. Carroll Pilant, shooter and long-time press liaison at Sierra, says tests of lead-free bullets have shown them not to be viable substitutes for lead. “Copper bullets won’t deliver the accuracy we get with MatchKings. We’d be foolish to replace an iconic bullet like the MatchKing—the choice of an overwhelming majority of competitive shooters.” Pilant hasn’t heard of anyone at a high-power match choosing lead-free bullets. Nor does he think copper bullets equal Sierra’s GameKing for either accuracy or devastation in deer-size game.

While Winchester and Remington have introduced their own lead-free bullets, Federal has not. Its preference: offer bullets from the nation’s top bullet-smiths. Jason Nash at Federal emphasizes that the firm has traditionally given hunters many options. “We’ll continue that policy, with bullets from our house and specialty lines like Nosler, Barnes, Sierra and Woodleigh.” Federal’s Trophy Bonded Bear Claw has a big following among elk hunters. The company is pursuing a viable lead-free .22 Long Rifle round.

As lead-free bullets gain traction at market, they’ll get more attention from engineers charged with improving them. At this writing, Dave Emary and colleagues at Hornady are designing GMX bullets that incorporate Hornady Flex Tips for rifles with tube magazines. “It’s not an easy assignment,” he confides. “Lead-core bullets obligingly grip the FTX peg. A gilding metal nose isn’t as malleable. Prototype bullets have spit out the soft tips during assembly.” He smiles. “I’m sure we’ll solve the problem.”

By the way, does the addition of a soft or hard polymer nose affect the terminal performance of a gilding metal bullet? “Our work shows a hard polymer tip can make expansion more violent,” says Dave, “especially at high impact speeds. An FTX tip does not. But it helps trigger upset at low velocities.”

Pointed noses and long ogives help bullets cleave air. But the form factor is just one component of ballistic coefficient, which includes sectional density. Reducing weight reduces sectional density. But how do the ballistic coefficients of two bullets of the same weight and nose profile compare if one is of jacketed lead and the other copper or gilding metal? The lead bullet has a slight edge, explains Dave. “The shank is shorter, so there’s less skin friction.” But the difference is small. A 165-grain 30-bore jacketed bullet with a ballistic coefficient of .450 beats its copper or gilding metal rival by only .015 or so.

Currently, lead-free bullets cost more than traditional jacketed bullets. That could change as more makers develop more bullets of copper and gilding metal. The industry has made this commitment, though only Remington calls its bullets non-toxic. Other companies share my view that non-toxic is an unfortunate moniker, as it implies that lead-core bullets present a hazard beyond that of a lethal wound channel. Science has yet to confirm any such hazard. Wayne van Zwoll has published a dozen books, more than 1,500 magazine articles and 3,000 photos about guns, optics and hunting. One of the Elk Foundation’s first field directors, van Zwoll holds a Ph.D. in wildlife policy from Utah State University. His Bugle column, inaugurated in 1986, is our longest running department.