Yeah especially since marines who ignore warnings that there is a mortar shot/CAS/OB incoming are usually not worth keeping alive anyway, since those are the types of people who get everyone else killed.
played mortar for the first time the other day, got like 15+ kills, it all comes down to knowing how to offset, organize shell types, wait for good commands to fire, but most of all
HAVING A COMPETENT SPOTTER THAT KNOWS WHAT THEY'RE DOING
From what I've been told, positioning is key. I've been trying to find good spots so I can get a good look at where the xenos are posted up at.
Being a competent spotter means being able to stand in one spot while everyone is running past you in both directions, getting a good set of coordinates for the enemy position, and then communicating those coordinates to the mortar officer with an order to hold fire. Then you need to remember the spot you gave, and start head calculating offsets for different scenarios, like xenos advance, xenos retreat, xenos try to flank. You have to see what patterns the xenos are following, then give the proper offsets & wait for the xenos to make the wrong move, then tell your mortar to fire. A very important part is to verify the mortar is on target, and adjust if it isn’t. Equally important, make sure to adjust if it IS on target if you want multiple shots to harass the xenos back during their retreat or advance.