No no no, thats completely false
. Puppetz, don't go trying to apply World of Tanks crap to Aces High.
What I mean is that past 1200yds, 'standard' AP rounds (actually they are APCBC, or Armor Piercing Capped, Balistic Capped) are more effective than HVAP (HVAP stands for High Velocity Armor Piercing. They're the same as APCR or Armor Piercing Composite Rigid)
Standard AP rounds are essentially just a big bullet. Face hardening of the armor plate was found to cause the rounds to shatter on impact. This led to APC rounds to be introuduced. It was a normal AP round, but with a cap of softer metal on the nose of the round to dampen the impact, and prevent the round from shattering. However, the caps were't the most aerodynamic, so they added a hollow nose to the cap that brought the APC rounds to the balistic standards of normal AP rounds. These became known as APCBC rounds.
An APCR or HVAP round is different though. It takes a small, sub-caliber dart, and surounds it with a lighter alloy, often aluminum. This makes the round lighter, which allows higher velocities to be achieved without using a larger propellant charge. However, the casing doesn't fall away like with APDS (Armor Piercing Discarding Sabot), so the rounds have the same overall dimensions as AP or APCBC rounds. Because they have less mass compared to their dimensions, they lose their effectivness faster, as they slow down at a faster rate than AP or APCBC rounds.
Kinetic energy translates to armor penetration, and KE = mass x velotciy squared / 2. Since velocity is squared, increasing velocity improves the preformance of a shell or bullet to a greater degree than increasing the mass of the projectile does. However, it also means that as velocity decreases, it also has a greater negative effect on the preformance of a shell.
All this means that, an HVAP shell will slow down faster than an AP round, and that lacking the extra mass compared to an APCBC shell, it won't penetrate as much armor as an AP shell, even when they are at the same velocity. As a result, HVAP shells will preform better than AP only out to a limited range (1200yds for the two HVAP shells we have in the game).