Green’s Dictionary of Slang

(US Und.) a house gambler who cheats the bettors at a casino.

1961		J. Scarne Complete Guide to Gambling 279: The professional bust-out man, concentrating on the task of switching in his crooked dice.
1969		B. Jackson Thief’s Primer 165: They started out dealing craps in my uncle’s joint and I’ve used both of them as bust-out men in my joint.