Green’s Dictionary of Slang

(US) a gambler.

1875		Chicago Trib. 10 Dec. 2/3: A Hard Place for Gams [...] The mayor has all the gambling-houses closed.
1884		Chicago Trib. 25 May 13/2: ‘I am a professional gam’.
1890		J.P. Quinn Fools of Fortune 368: I guess you ‘gams’ knows who I is [HDAS].
1903		A.H. Lewis Boss 291: Them gams took it [i.e. ‘the long green’] off him so fast he caught cold.
1920		Ade Hand-Made Fables 46: He surely knew how to throw a scare into the Gams.