In 2016, Shell Shock Technologies introduced the world’s first two-part ammunition case: a two-piece, all-metal small-caliber design unlike anything the industry had produced before. It was such a departure from convention that the technology is protected by three separate patents across multiple countries.
Today, other manufacturers are pursuing multi-piece case designs, further validating the advantages of this approach. Here is why the two-piece design matters, and what it delivers that a traditional brass case cannot.
Brass has served shooters faithfully for more than 100 years. But nothing stays the single best solution for a century. That thinking is exactly what drove the search for a better-performing case.
The function of a fired cartridge comes down to three fundamentals:
The catch is that any improvement has to work seamlessly in legacy firearms and existing manufacturing processes: no compromises on compatibility.
A conventional brass case is one integrated piece. Its heavy base is required to contain internal pressure, but that mass also eats into internal volume. The two–part ammunition case solves this by separating the base structure from the cylinder wall, so each part can be engineered for the job it actually does.
Instead of brass, the case cylinder is formed from a nickel-stainless steel alloy, roughly 7% lighter than brass and about four times stronger, and easily formed with the modern alloys available today.
That strength-to-weight advantage allows for a much thinner cylinder wall, reducing overall weight while leaving more room inside the case. The base uses a high-strength stainless steel component joined to the cylinder through a riveted connection.
That base is where the material advantage matters most. A conventional brass case has a yield strength of about 66,000 PSI; pushed beyond that point, brass deforms permanently, releasing the primer and jamming in the breech. The Shell Shock Technologies high-strength stainless steel base has a yield strength of roughly 150,000 PSI, giving it the headroom for the high-pressure cartridge classes the U.S. military is now targeting.
Unlike traditional steel cases, the nickel-stainless steel alloy is lighter than brass, gentler on extractors, and designed for smooth, reliable ejection.
Separating the two parts lets the design capitalize on the strength of each without sacrificing the features that matter. A key payoff is internal volume.
Because the base no longer needs the bulky, integrated brass bottom, the two-part ammunition case offers increased internal volume. More room means more efficient use of energy when the powder charge ignites, which supports higher velocities at standard SAAMI pressures compared to traditional brass cases. In rifle calibers, that added room translates to roughly 10% to 12% more powder capacity than conventional brass cases on average.
For more on the standardized pressure specifications that govern safe ammunition performance, see the SAAMI standards.
The two-piece architecture also made room for a patented wave feature built into the cylinder. When the case fires, this feature pushes the case forward, something a one-piece brass case simply cannot do.
That forward motion seats the projectile into the barrel rifling as it releases from the case, reducing alignment issues and wobble as the bullet travels down the bore. Shell Shock Technologies’ testing has demonstrated accuracy improvements of up to 200% in certain testing.
There is an ergonomic bonus, too. The stainless base is magnetic, so spent cases can be gathered from the ground with a simple magnet.
Brass is not magnetic, which is why ranges are so often littered with brass cases left behind. Easy cleanup is a small feature that shooters notice every session.
The two-part ammunition case reimagined a component that had barely changed in a century, delivering lighter weight, better accuracy, and more efficient energy in a package designed for compatibility with existing firearms and ammunition manufacturing processes.
Learn more about the technology, explore the full lineup, or read related articles in the Shell Shock Academy.
