Instead of manual firing mode i would just give them two type of shells which should be switched manually when the situation requires is. Switching shells should come with a long cooldown (like 30 or 40 sec) so it could not be done rapidly.
ISU-152:
Concrete-piercing shells:
- High range (around 80)
- High armour penetration (effective against german heavies)
- Small AOE (ineffective against infantry)
- for AT purposes only
HE or High Explosive shells:
- Smaller range (around 60)
- Low armour penetration (still good against light vehicles)
- Large AOE (chance to eradicate infantry squads)
- for AI purpose only
JagdTiger:
Concrete-piercing shells:
- Ability to fire through any obsticles
- Less damage or Penetration
- Smaller range (around 70 or 80)
AP or Armour Piercing shells:
- Full range (around 90-100)
- High penetration and damage
- Cannot fire through any obsticles
With these changes both tank could keep their abilities and roles, but players should make tactical decision which shell do they use in which situation. In other words you cannot use these units so carelessly, because with the wrong type of shell your tank wont be so effective, not even when it auto-fires. Im not telling you these changes could completely fix the units, but i think these could be a start to the right direction.
What do you think?