The DUF-3x22 is an unlicensed black market flechette manufactured in illicit workshops using depleted uranium alloy instead of the standard tungsten-ceramic composite of the legitimate TCF-322. The depleted uranium core provides approximately 20% greater mass in the same dimensional envelope, which translates to increased kinetic energy at the same muzzle velocity and enhanced penetration against hard armor that tungsten-ceramic flechettes cannot defeat.

The flechettes are designed as a direct dimensional replacement for the TCF-322, fitting into standard GFR-3 sealed cassettes that have been opened, reloaded, and resealed by black market armorers. The cassette resealing process is imperfect — the electromagnetic advancement system works with the heavier DU flechettes, but the increased mass causes accelerated barrel wear and coil degradation in the weapon, reducing the GFR-3's service life by approximately 40%. Operators who fire DUF-3x22 ammunition accept this trade-off knowingly, treating the weapon as a consumable.

The depleted uranium also presents a radiological hazard. While the radioactivity of DU is low, the fine ceramic-analogue dust produced on impact is both chemically toxic and mildly radioactive. Targets hit with DUF-3x22 flechettes at close range inhale uranium dust, producing long-term health effects that may not manifest for years. The operators themselves face exposure risk from handling the ammunition and from aerosolized DU in enclosed firing environments. Black market DUF-3x22 flechettes are not accompanied by safety data sheets.