The only problem I see with FMJ's would be if the FAM has to shoot at the bad guy who is between him or her and the cockpit. Super penetrating rounds heading toward the only people who can land the airplane. A little armor plating behind the cockpit might be in order...
Cockpit door is reinforced and “bullet proof”. One of the mandated changes after 9-11. Plus, there’s at least two of them in there......only takes one to land, so they’ve got a spare.