SABOT rounds

[Marek_Tucan]

Originally Posted by Suhiir

Keeping good old E=MC2 in mind

Nitpick Not E=m*sqr(c) as the round does not annihilate and if it did, this energy is independent on velocity, but E=0.5*m*sqr(v) Also momentum is important, p=m*v

To add to theory, SABOT rounds tend o have different ranges in-game. Why? Because they are of different types and generations. To put it roughly, you can have:
APCR/HVAP (Armor Piercing Composite Rigid/High-Velocity Armor Piercing) - shot with subcaliber body and rings of light metal attached to it to seal the barrel (also called "arrowhead" etc.). Light, with penetrator from hard and dense metal (sually tungsten, or maraging steel). Used during and after WWII, effective at short ranges because their small mass combined with high drag (given by full bore diameter) slow them down considerably.
APDS (Armour Piercing Discarding Sabot) - designed by Brits during WWII, these have subcaliber hard and dense core and sabot that detaches upon leaving barrel, thus giving much lower drag to the round, apart from high velocity. In use for a long time.
APDSFS (or APFSDS) - Fin-Stabilised Discarding Sabot, "arrows" with fins on one end, tendency is to have them as thin and as long as possible. Thin to get the shot energy on a small area, long to get the mass required to gain the energy. Most modern penetrators have diameter of some 22-24mm. Materials vary, usually some tungsten alloy or tungsten or depleted uranium, though Soviets made rounds from maraging steel for export and training use (it seems that those BM-17 rounds were the only Sabot rounds used by Georgia in recent conflict and Russians didn't have much better, with HEAT being also 70's stock so bot side's T-72B cannot penetrate their opposite numbers from the front). Russian APFSDS also limited by short length of separate loading 125mm ammo. First generations suffered problems with stability, so new rounds often have lower velocity compared to the older ones, to be more accurate, and higher penetration is acquired by other means. Range-wise, the thinner the round, the longer range and less velocity drop it experiences.