Cover System?

[Lunarea]

You'd only need to terrain tag a piece of floor that's on the ground behind the object to, say, 3. Then, one parallel process event checks if the terrain tag of the shooter is lower than the terrain tag of target and flips a switch. If the switch is flipped, no shooting happens or "miss" graphic pops up. You can even make it easier on yourself and the player by having a visual reminder of the tagged areas.