120 mm M865 TPCSDS-T

468.5 mm steel rod with a pierced tailcone used for in-flight stabilisation. The steel tailcone also acts as the range reduction component, depending on an established aerodynamic principle referred to in Germany as the Lochkegelleitwerk (pierced tailcone), or LKL. For the LKL principle to operate, the nine holes in the tailcone are accurately machined to a size where, at high velocities, they are aerodynamically open and air can pass through without significant hindrance. As the projectile velocity reduces with range the holes aerodynamically close at a certain velocity. This leads to an increase in drag and the projectile becomes unstable to the point where it will fall to the ground at a maximum range of approximately 7,500 m. This aerodynamic change takes place after the projectile has travelled about 2,000 m. Up to that point the M865 projectile follows the same ballistic trajectory and is as accurate as the normal M829 operational projectile. The result is that range safety traces can be reduced to as little as 8,000 m in place of the 30,000 m plus required for firing ranges where operational M829 series APFSDS-T rounds are fired. The M865 steel projectile is carried in an aluminium three segment discarding sabot assembly secured in a normal CCC. The CCC contains approximately 7.5 kg of M14 granular nitrocellulose multiperforated (19-hole) single-base propellant in a containment bag, which prevents spillage in the event of a rupture of the combustible case walls; the propellant is produced by ATK at the Radford Army Ammunition Plant in Virginia. Although described as combustible, case ignition does leave the steel base stub intact for ejection from the gun after firing. The insulated electrical primer was designed to be cool to the touch following stub case ejection. Muzzle velocity is 1,700 m/s (±12 m/s) and maximum effective range 2,500 m.