Green’s Dictionary of Slang

1. (orig. US) a .38 calibre pistol; also attrib.

1907		W.M. Raine Wyoming (1908) 61: The boys don’t like seeing your hardware so prominent at a social gathering [...] I’m a committee to mention the subject and to collect your thirty-eights.
1927		B. Cormack Racket Act I: Why, anybody who carries less than a thirty-eight in this town’s a fairy.
1934		R. Chandler ‘Finger Man’ in Pearls Are a Nuisance (1964) 74: I [...] drew out a long .38 with a six-inch barrel.
1947		S.J. Perelman ‘Farewell, My Lovely Appetiser’ in Keep It Crisp 9: Snapper Driscoll had retired two years before with a .38 slug between the shoulders.
1953		‘William Lee’ Junkie (1966) 16: Give me a thirty-eight every time. Just flick back the hammer and let her go.
1964		R. Abrahams Deep Down In The Jungle 132: I had that old bad-ass Benny Long in my 38 sights.
1965		B. Jackson Get Your Ass in the Water (1974) 48: About that time the poor boy was dead / with three of my thirty-eight rockets in his head.
1972		G.V. Higgins Friends of Eddie Coyle 9: I’ll take four-inchers. Thirty-eights. I’ll take a three-fifty-seven mag if I have to.
1985		N. Pileggi Wiseguy (2001) 84: Tommy always carried his gun in a brown paper bag [...] he looked like he was bringing you a sandwich instead of a thirty-eight.
1996		Bynum & Thompson Juvenile Delinquency 290: Tray eight. .38 caliber handgun.

2. (orig. US) a bullet from a .38 pistol.

1909		Witchita Dly Eagle (KS) 26 Dec. 9/3: The edge of his shoe turned up something [...] which proved to be a thrity-eight USS & W shell.
1930		R. Whitfield Green Ice (1988) 20: ‘Angel’ Cherulli had been found in an alley behind his club, with a flock of thirty-eights in his stomach and chest.
1985		N. Pileggi Wiseguy (2001) 191: Lying under the covers of a bed in his Ozone Park apartment with six .38s in his chest and head.