Green’s Dictionary of Slang

1. (also am, ami) ammunition; also attrib.

1911		q. in B. Tuchman Stilwell and the American Experience in China (2017) 51: Many had new ammo belts and plenty of cartridges, some were standing around pistol in hand, finger on trigger.
1917		A.G. Empey Over the Top ‘Tommy’s Dict. of the Trenches’ 282: ‘Ammo’. Rifle ammunition. Used to add weight to Tommy’s belt. He carries 120 rounds, at all times, except when he buries it under the straw in his billet before going on a route march. In the trenches he expends it in the direction of Berlin.
1925		(con. WWI) Fraser & Gibbons Soldier and Sailor Words 6: Ammo, ammunition, e.g., Ammo depot, Ammo store, etc.
1937		J. Archibald ‘Crash on Delivery’ in Flying Aces Nov. 🌐 He stood near the ammo shack idly smoking a cigarette.
1941		G. Kersh They Die with Their Boots Clean 2: There lies both scouts with knife-holes in their backs and their rifles and ammo gone.
1953		L. Uris Battle Cry (1964) 193: Danny [...] loaded up a couple of ammo clips.
1962		R. Cook Crust on its Uppers 103: ’Ere’s the ammo for it.
1972		G.V. Higgins Friends of Eddie Coyle 22: You could get me some three-fifty-seven and forty-one ammo.
1979		J. Morrow Confessions of Proinsias O’Toole 38: We haven’t been lumbering him with duff ammo.
1986		S. King It (1987) 234: It was an ammo dump.
1991		R. Doyle Van (1998) 612: It’ll be ammo for yeh, compadre, Bertie’d said.
1999		K. Sampson Powder 98: He’d handed her the pistol and a spare round of ammo for good measure.
2008		T. Dorsey Atomic Lobster 125: Nothing builds confidence like live ammo.
2010		L. Redhead Thrill City [ebook] How much ammo you got?
2015		410 ‘Four Door Coming’ 🎵 Mana got links for the am bits, might have to rob me a plug.
2015		67 ‘Hookahs’ 🎵 Ring ring, trap, trap, I phone up my bro, he got ami in packs.
2016		Jamaica Obs. 14 Mar. 🌐 Four guns, ammo, saeized in 24 hours.
2019		S.M. Jones Lives Laid Away [ebook] We selected our primary weapons and ammo.

2. semen [fig. use of sense 1; note also earlier ammunition n. (1)].

1942

‘Lagos Lagoon’ in M. Page Kiss Me Goodnight, Sgt.-Major (1973) 56: He fired all his ammo while well out of range.

3. (US Und.) money [fig. use of sense 1].

2003

H. Hill A Good Fella’s Guide To N.Y. 123: Candy, markers, ammo, liners, stocking stuffer, sweetener, garnish, and pledges are all terms for cash.