I'm thinking I read somewhere along the way that SAG or some other actors organization had guidelines that included not ever having live ammunition on set and she allowed live ammunition on set - and didn't control it by keeping it locked up."The armorer who wasn’t even there, probably not. No way could she be in any kind of control if she was in fact helping wardrobe."
IIRC, they were having a labor dispute (partially about gun safety due to negligent discharges [with LIVE AMMO?]). Could one of the unhappy people have squirreled away a live round or two to insert in a 'cold' prop gun to prove a point? Were I a lawyer, I might think about using this, although it probably would hurt him as far as proving negligence...