Special artillery Units

[J_Irons]

This game is a masterpiece, a simulation game so it’s more than a wargame so how do you use (according to the game rules - T/D mode - direct/indirect fire) these units:

7.5 le.IG 18
15 s.IG 33
15 cm sIG 33 (Sf) auf Panzerkampfwagen I Ausf B
4.7 cm Panzerjager I

I’m curious if anyone uses the Wehrmacht tecnics, or if these are suitable to the game mechanics

Thank you in advance