Okay simply enough can marines shoot each other? Not like an accidental hit with a flamer but actually shoot another marine with a stormbolter.... The rules say you can target genestealers and doors... But as you can shoot your own guys with the flamer why not a stormbolter?
Let me explain. I have included a diagram of the situation.
We were playing the first mission, 'Space marine B' has used up all his action points and the squads one command point shooting genestealers and blowing up the door. 'Flamer Marine C' needs to fire his last flamer shot into 'objective room X' but his line of sight is blocked by 'Space marine B'. Can 'Sergeant marine A' shoot and kill 'Space marine B' so that 'Flamer Marine C' can take his last shot at 'objective room X' and win the game or is he doomed to be swarmed by 'Hordes of genestealers O'?
Although this isnt covered in the rules which would suggest otherwise as shooting is always referred to as targetting genestealers. But seeing as you can flame your own guys, why not be able to shoot them if victory relies upon it?