[Marcello]

I have done some digging and found the following.

Leclerc
Source 1
medium error of stabilization: 0,1 mrad vertical - 0,1 mrad horizontal

Source 2
medium error of stabilization 0,15/0,20 mrad vertical - 0,3/0,4 mrad horizontal

Leopard 2A4
medium error of stabilization: 0,15/0,20 mrad vertical - 0,3/0,4 mrad horizontal

M1A1
medium error of stabilization: 0,15/0,20 mrad vertical - 0,3/0,4 mrad horizontal

T-90 (not specified which variant)
medium error of stabilization: 0,4 mrad vertical - 0,6 mrad horizontal

Pinch of salt applies.