Modern Ammo Types With World War Two at an end, there was more time to devote to ammo research. A big development after the war was fin-stabilization. This is now used on all anti-tank rounds that are used today. With HEAT being rarely used in the war and only by Germans, the United States fought to develop a better HEAT round. The problem with HEAT in World War II was that it couldn't penetrate the thick armor that was being used near the end of the war. So research and development continued to try and create a more energetic round. The problem that was found was that spinning the round was causing a lot of lost energy to occur. The solution was to use deployable fins to stabilize the round as it travels, being called HEATFS. The round was able to keep a lot more energy, therefor being able to penetrate the target a lot better. Even though there were major developments in HEATFS, there were also technological advances in tank protection such as reaction armor and spaced armor. The reactive armor would explode and push the HEATFS shaped charged away from the tank, rendering the shell useless. There was also shaped armor. The charge would hit the armor that is spaced away from the main armor and explode, causing the explosive to not penetrate and harm the crew. This is when APFSDS came into production. This is purely a kinetic round that travels at supersonic speeds to reach its target. These rounds are used in all modern tanks like the American M1A2 Abrams and the British Challenger II. The actual projectile isn't the size of the 120mm guns that most modern tank have, it fits snug inside a SABOT which discards immediately after it leaves the muzzle. It is about the size of a dollar coin. Even though most of this round's information is kept a secret, it can penetrate hundreds upon hundreds of millimeters of armor, which is why it is used today.