[The Son of Horus]

The accepted practice around here is to roll to see if it overheats anyway, since the shooting unit doesn't necessarily know they're out of range, even if you do. In the rules, it says that the unit simply misses if they're out of range, which implies that someone has pulled the trigger. Either simply not worrying about it, or rolling to see if the plasma weapons overheat is fair game, I think.