His foolish statements provided his opponents with more 'ammunition' to use against him in the campaign.
She had the 'ammunition' to prove her case. [=she had the evidence she needed to prove her case]
The troops were supplied with weapons and 'ammunition'.
(..) He's been shot dead, idiot. Don't you call me an idiot. What? Who's that? Be careful, darling. Well, he's either reloading or out of ammunition. He's out of his mind. That's what he's out of. I'll kill him. I'll kill him. Monsieur! (..)1975 The Return of the Pink Panther