13.0 Do Mortars Get a +1 Shift on OP Fire?

[plloyd1010]

In my opinion they should get the +1 modifier, OP fire is when a unit is moving, and as such it is venerable to increased casualties due to it being exposed, especially infantry, so if a unit can take extra casualties due to DF do not see why the +1 modifier would not pertain to mortars using OP Fire.  Was under the impression the venerability of the moving unit that the +1 modifier is representing (my interpretation).  Interesting topic. 

There is obviously no such modifier, applicable or otherwise, on the bombardment table. Furthermore, Drumfire from IA and the PG options, do not have such a modifier against moving targets. What you want is a house rule. Are you arguing that mortars (lobbing bombs) can be aimed as accurately as rifles and machine-guns?