US Army unveils polymer 'SixPAC' ammo crates to replace legacy metal boxes

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Publication date: 2026-09-01 12:23:54

Since World War II, the United States Army’s small arms ammunition has evolved significantly. The service replaced the venerable .30-06 Springfield and .30 Carbine cartridges with the 5.56x45 NATO round during the Cold War, and is now transitioning to the advanced 6.8x51mm common cartridge — also known as 2.77 Fury. This new round was developed to bridge the gap between the legacy 5.56x45mm and the heavier-hitting 7.62x51mm cartridges used by the U.S. military and its NATO allies. The Pentagon hopes the new cartridge could eventually become a NATO standard.

However, while cartridge development has advanced steadily since WWII, the way ammunition is packaged for troop distribution has seen little to no improvement — until last month.

The U.S. Army Combat Capabilities Development Command Armament Center announced the introduction of a new polymer packaging system, marking the first major overhaul of small-caliber packaging since the days of the "Greatest Generation."

The Metal Ammo Box Has Met Its Match

The old metal ammunition boxes are arguably one of the greatest military inventions of all time. Beyond carrying ammunition effectively, these sturdy boxes are widely used in the civilian world for tools, camping gear, and other items.

Ammo boxes have been a staple of army/navy surplus stores across the country for decades, though not all are technically "surplus" — there is no shortage of non-military knockoffs.

Yet, the old ammo boxes have finally met their match.

The new polymer containers offer comparable strength but weigh only half as much as legacy steel ammo boxes, reducing the load carried by soldiers in the field.

It is expected that more than 800 injection molders across the country will be capable of producing the crates, saving the Pentagon and taxpayers money while lowering the barrier to entry for new suppliers.

Grab a SixPAC

The new packaging, dubbed the "SixPAC" for its capacity to hold 6.8mm cartridges, features two lightweight polymer ammunition containers housed in a steel outer pack.

"After successful implementation with the cartridges, the system is planned for adaptation across multiple legacy small-caliber ammunition production lines," the Army announced last week.

This change does not contradict the old-school thinking of "if it isn't broken, don't fix it." Rather, it was part of an effort to address supply chain vulnerabilities, rising costs, and the need to prepare for future military operations in varied climates.

These concerns led to a "reevaluation" of legacy munitions packaging.

The new SixPAC offers a lighter tactical inner pack, which could expand the manufacturing base and increase efficiency. The polymer system also removes wood entirely from the equation, as the old heavy metal ammo boxes were transported in wooden crates.

Those crates were manually assembled and susceptible to mold during storage. By switching to polymers, the process is simplified, and there is reduced reliance on chemical treatments previously required for wood, lowering environmental impact.

The polymer inner pack enables easier transport, while the steel outer pack reduces the logistical footprint. This allows more containers and ammunition per pallet and draws from a notably larger supply base than its legacy wood counterpart.

"It's a developing field, and polymers are unique — you can modify them, include additives that improve impact performance, stiffness or dimensional stability," said Edward Lucas, a mechanical engineer and polymer designer at the Development Command Armament Center. "You can add more ingredients to the cauldron and your potion will come out different, trading some characteristics for others."

Evolution of Ammunition Crates

Polymer is the latest step in the evolution of ammunition crates. The earliest form of small arms ammunition packaging...