When shooting at a war machine shots are worked out against the entire model and any hits scored are randomised against the crew and machine. This is essentially the same procedure as for shots at characters riding large monsters and for chariots.

War machines and their crews generally constitute a large target (more than 10' high or broad in real terms) and so the shooter benefits from a +1 to hit bonus.

Once hits have been established randomise where they strike as shown below.

Once all crew are slain, or if they flee, or once the machine is destroyed, further hits do not need to be randomised but will strike a crewman or the machine as appropriate.