A tank is a fast-moving, well-protected, heavily armed behemoth designed to dominate the land battlefield. As the primary offensive weapon in any army, nations compete to field the best tanks in both peace and war. In the 1980s, the U.S. Army took the drastic step of arming its tank, the M1 Abrams, with the ultimate upgrade: a tank-killing round made of uranium, the heaviest naturally occurring element on Earth. The result is an unmatched tank killer capable of destroying any fielded tank.
The M1 Abrams tank was first fielded by the U.S. Army in the 1980s. The Army had preferred the 105-millimeter gun, the British-designed Royal Ordnance L7, also known in the United States as the M68. The M68 had armed the M60 series of tanks for decades and was considered a proven “good enough” gun. The M1’s turret could only accommodate fifty-five rounds of 105-millimeter ammunition, a reduction from the sixty-two rounds the older M60 tank could carry. An even larger gun would further reduce ammo capacity to a mere forty rounds.
Pentagon officials, on the other hand, wanted to equip the M1 with the larger German-designed Rheinmetall M256 120-millimeter smoothbore gun. The civilian leadership felt obliged to use the gun in part as a way to offset German participation in the NATO AWACS program. A larger gun would also “future-proof” the M1, allowing it to defeat future tanks with heavier armor. A compromise resulted, in which the M1 would be initially manufactured with the M68 gun, but would be upgradable to the M256 at a later date. Moreover, a later version of the tank, later called M1A1, would come standard with the larger M256.
While the tank was now future-proofed, the point about smaller ammunition capability still stood. The fire control system on the M1 was so advanced that it could hit a moving target at two thousand meters with 90 percent accuracy. The problem was not going to be missses and wasted ammunition, but ensuring that hits translated into kills.
At the same time, the United States was researching the use of depleted uranium as an armor penetrator. A byproduct of nuclear reactor fuel, depleted uranium was harder and denser than existing tungsten-tipped penetrators. Accelerated to extremely high speeds, this allowed a depleted-uranium (DU) round to smash through an unprecedented amount of armor. The pyrophoric nature of uranium and steel would cause the DU to catch fire upon penetration, causing catastrophic damage inside the tank.