It's Time to Replace the Rifle Cartridge

Apr 24, 2023

We’ve seen almost nothing truly innovative or novel in rifle cartridge design in well over a century. Let's go already

By David E. Petzal | Published May 26, 2023 8:46 AM EDT

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ECCLESIASTES 1:9 READS: "What has been will be again. What has been done will be done again. There is nothing new under the sun." This brings to mind the 6.5 Creedmoor and inspires the biblical rant to follow. The 6.5 Creedmoor is a conventional cartridge that's no different from any other conventional cartridge, and yet people go nuts over the thing. And it's not new; it has morphed from what has gone before. It's just more proof that there's hardly anything really new in the world of guns.

What's the fastest commercial cartridge? It's the .220 Swift, which produces a muzzle velocity of 4,600 fps. When was the Swift developed? In 1935. What cartridge was it based on? The 6mm Lee Navy, a service cartridge that was declared obsolete in 1895. Can any sporting rifle cartridge outspeed the 88-year-old Swift? No.

Here's something that must be new: In 2019, the U.S. Army, in conjunction with SIG Sauer, announced a new round called the 6.8×51 Common Cartridge. Why "Common?" Because it's intended for dual use in the Army's new infantry rifle, the XM5, and in its new squad automatic weapon, the XM250. It was, the announcement said, the first time in 60 years that the service was introducing a new bullet diameter. Well, new for the Army. A 6.8mm bullet is .277, as in .270 Winchester, which is of 1925 vintage.

What makes the Common Cartridge special is that it's far more powerful than the 5.56 NATO. It fires a 140-grain bullet at 3,000 fps from a 16-inch barrel. But how does it achieve such velocity? The pressures must be insane. They are. The 5.56 NATO operates at 62,000 psi. The Common Cartridge cranks up 80,000 psi, which is Get-Right-With-God pressure.

How did SIG manage this? By strengthening the case head, which is the weak point of any shell. The head of the Common Cartridge case is steel, which is screwed into the brass case and held in place by an aluminum lock washer. It can handle 80,000 psi just fine. Ingenious? Yes. New? Not exactly.

In 1984—that is, nearly 40 years ago—the O’Connor Rifle Products Company of Edisto Island, S.C., introduced what it called Steelhead Cases. These were unformed brass cases threaded for hardened-steel heads. They came in .30/06 and 7mm Remington sizes, and you adapted them to your caliber by running them through a series of sizing dies and then fire-forming them. As I recall, O’Connor Rifle Products also recommended the use of dual powder charges*—a small charge of a fast powder first, and a bigger charge of a much slower powder. The purpose of all this was to allow you to get magnum velocities in a standard rifle, and super velocities in a magnum rifle. I had a box of the .30/06 size for years but was too chicken to use it. If you try mixing powders or using dual charges, you may get away with it, or your friends may end up calling you "Stumpy."

But surely there's something new out there. Well, there is, sort of. Back in the 1960s, a California company called MBAssociates developed a line of handguns, carbines, and rifles that used projectiles called Gyrojets. These were miniature rockets, not cartridges, and they burned rocket fuel, not gunpowder. In operation, the rocket fed up from a magazine, and when you pulled the trigger, a hammer mounted in front of the rocket snapped backward and smacked the rocket on the nose, driving it onto a fixed firing pin. The rocket left the gun slowly, picking up speed until it reached about 1,200 fps.

I got hold of one and found that there was hardly any noticeable recoil, but neither was there any noticeable accuracy. If you were standing in Austin with a Gyrojet, you might be able to hit Texas. There were advantages to the system, but too many problems, and as we were gearing up for Vietnam, the idea was scrapped. But was it new? Yes, it was, and we might see it again someday.

The other genuinely new "gun" is the U.S. Navy's rail gun, which had its plug pulled in 2019 after 15 years of development and $500 million spent. The rail gun is a linear motor device that operates on electromagnetic force. The first (very small) one was developed in 1917, but the Navy picked up on the idea again in 2005, and built a great big one to be mounted on the deck of a warship. What a rail gun can do is impart enormous velocity and kinetic energy to a 23-pound aluminum projectile filled with tungsten pellets. Imagine such a projectile traveling at Mach 8 (8,695 fps) with a range of 110 miles, and enough kinetic energy to sink a ship when it hits.

The problem with rail guns is, they require a colossal amount of electric current. To fire a projectile, a rail gun requires 25 megawatts, or the output of an entire civilian power plant, for one second. Because of this, they generate a massive amount of heat, burn out very quickly, and have to be rebuilt at great expense. They’re not accurate enough either. So, the Navy gave up on the idea and went with hypersonic rockets.

The Navy rail gun is 30 feet long and weighs 40 tons. This would be awkward as shoulder-fired ordnance. But who knows what the future holds? Hunters of the future may carry rail guns and have power packs strapped to their backs. I will not be among them.

That we haven't seen much of anything truly innovative in the design of firearms or cartridges in more than a century is disappointing. Do I think we’ll get there? Yes, sooner or later, and probably sooner. The days of the internal combustion engine are probably numbered, and it will be replaced before too long. I’ve heard fighter pilots speculate that these engines are in their final decades, and that they will be replaced before very long by drones. AI will do what? No one knows. Guns, as we know them, have been evolving since the Middle Ages. It seems almost inevitable that something radically different will come along and replace them before too long.

In the meantime, modern ammunition is expensive, dirty, and probably not capable of much more improvement (although I may be dead wrong about that). But it works. In fact, it works unimaginably better than it did when I began shooting. So why worry if the Phaser is not on the horizon? Besides, there are few things in the world that smell as nice as gunpowder smoke.

*I have to mention that dual-powder ignition does have a use, and it works fine…in the larger naval guns. The powder charge for a 16-inch gun—the kind that comes three to a turret—consists of six silk bags holding 648 pounds (each) of cordite. The base of each bag contains a small charge of black powder, and there is a "thread" of black powder running up through the center of the cordite charge. Since black powder ignites very easily, the Navy can utilize a primer about the size of a shotgun shell to set the whole thing off. (If you’re thinking of experimenting with a 16-inch naval gun, be sure to call the ATF and get a Class 3 license first.)