The U.S. Army Combat Capabilities Development Command Armaments Center has introduced SixPAC, a polymer and steel ammunition packaging system designed to replace the wood wirebound boxes that have been standard for small-caliber munitions since World War II. The system consists of two lightweight polymer inner containers housed within a steel outer pack, initially developed for 6.8mm cartridges and planned for rollout across legacy small-caliber production lines.

Unfortunately, this Press Release only came with one image of the new SixPAC system, taken by Eric Kowal, U.S. Army, and featured above. However, quite a few more images of the current systems were provided and will be used below.

Below: Image by Marine Corps Lance Cpl. Donovan E. Melendez.

The polymer inner packs are expected to weigh approximately half that of existing steel M2A2 containers. This weight reduction directly impacts soldier loadout capacity, particularly for weight-constrained platforms including watercraft and aircraft, where additional payload affects launch capability and platform agility. The system eliminates the traditional wood outer box, which, according to the Army, required regular remediation, manual assembly, and was subject to mold growth. Another upside is that the removal of chemical wood preservative treatments reduces environmental exposure.

The injection molding process used for polymer inner pack production creates manufacturing redundancy. More than 800 injection molders operate within the United States and are capable of producing these containers. The same production press can switch between different mold configurations for alternate products, eliminating the need for large dedicated fabrication lines or extensive tooling investment. This flexibility lowers barriers to entry for new suppliers and increases competitive manufacturing options.

The polymer formulation remains under active development. Senior Scientific Technical Manager for Packaging Jason Runell stated the material selection emerged from necessity rather than preference, as polymers lack the long-term proven track record in U.S. military service that exists in other nations. The requirement to operate across varied climates and meet performance standards after extended storage drove the material selection. Edward Lucas, mechanical engineer and polymer designer at the center, noted that polymer additives can be modified to optimize impact performance, stiffness, or dimensional stability, with each adjustment creating different performance trade-offs.

Soldier testing occurred throughout 2024 and 2025. Field feedback was characterized as “valuable” and “much of it positive,” with service members noting that weight reduction enables increased ammunition carriage, particularly aboard watercraft and aircraft. The Polymer Rectangular Container (PRC), a patent-pending design, is undergoing continued refinement. The Armaments Center plans to share performance requirements, dimensional constraints, and lessons learned with industry partners to support broader development.

U.S. Army SixPAC Small-Caliber Ammunition Packaging System

• Composition: Two lightweight polymer ammunition containers (PACs) within steel outer pack
• Initial application: 6.8mm small caliber ammunition
• Planned deployment: Multiple legacy small-caliber production lines
• Inner pack material: Polymer formulation with additives for impact performance and dimensional stability
• Outer pack material: Steel
• Weight reduction: Inner polymer packs expected to weigh approximately 50 percent of legacy steel M2A2 containers
• Manufacturing process: Injection molding for polymer inner packs
• Supply chain: More than 800 U.S.-based injection molders capable of producing containers
• Production flexibility: Same manufacturing press accommodates multiple mold configurations without dedicated fabrication lines
• Environmental impact: Eliminates chemical wood preservative treatments required for legacy wood boxes
• Testing period: 2024-2025
• Status: Polymer inner pack design undergoing refinement, multiple container designs under evaluation
• Patent status: Polymer Rectangular Container (PRC) design pending patent protection