The game system uses
HE AP kill for air guns (times number of AP as a multiplier of cannons).
Therefore there is absolutely no point in putting a tungsten AP round (and simply upping the HE-AP would lead to mass destruction of all "splash" hits).
The system SSI decided on works OK for multiple HMG, 20mm cannon etc. It does not really work well for flying gun type tank killing planes - but there were precious few of those in any case. If they
had been wonder weapons - the warring nations would likely have made more of the things, methinks
Cheers
Andy