The perfect balance of the fans rotating at a gazillion rpms knocked off balance via anything ingested would cause the engine to self destruct and if damage was slow enough the imbalance would be analogous of a blowout of the tire on yer family cruiser only a hundred times faster or better. Now that cotter pin can be a nut with a bullet or just a nut dropped by the mechanic on the runway etc etc
Golden BB theory is valid, and has worked against even the best and fastest of military aircraft. A shooter laying amoung the VASI lights at the departure end could do the deed.
As to TM's suggestion about National Guard/Wooden Indian comments, I agree 100%. They should be looking versus just looked at.
Of course, those weekend warrior clerks and cooks would have to be taken to the range to learn to fire their rifles, which I have no doubt have cobwebs in the chambers.
If they even have bolts, or loaded magazines.