Well it figures I found out the information from the net myself after some digging.
BT-42 was capable of indirect fire and it was designed as an SP Artillery piece primarily. Due to poor leadership decisions it was pressed to direct fire role with disasterous consequences.
Sorry for raising false alarms. The unit seems to be modeled correctly.
...Though it did have HEAT ammo... Althought the HEAT ammo was quite useles. It could not penetrate T-34 armor. Due to the slow muzzle velocity the projectiles had a tendency to bounce off harmelesly. Probably bad fuzes too... The ammo was based on German 105mm shells modified to fire from the 114mm gun.
Not suggesting you should add Heat ammo for the unit ingame though
I do know that it was supposed to penetrate 100mm of armor at 60 degrees. In practice the HEAT projectiles malfunctioned and were quite useles.