Green’s Dictionary of Slang

to attain, to reach, to achieve.

1848		‘Ned Buntline’ Mysteries and Miseries of N.Y. III 53: Maria comes it the heaviest – she has a thousand!
1852		in N.E. Eliason Tarheel Talk (1956) 265: Who [the senatorial committee] will be it is difficult to predict, but my opinion is Old —— will not ‘come it.’.
1858		‘A. Pendragon’ Queen of the South 53: To be done, by a Methody cove, out o’ two bottles o’ rum [...] is a comin’ it too stiff.