For years Mickey Rooney had portrayed Hollywood's all-American teen, but at the age of 27 he was eager to move into grown-up dramatic roles. So he laced up the gloves as feisty boxer Tommy McCoy and scored a resounding box-office K.O. in the hard-hitting Killer McCoy.The story - a retelling of 1938's The Crowd Roars - traces McCoy's rise from slum kid to lightweight title contender. Along the way, he falls under the sway of a big-time gambler (Brian Donlevy), copes with his boozed-up pop (James Dunn) and finds forbidden romance with the gambler's daughter (Ann Blyth). But will he take a dive in the big fight? Don't expect Killer to be some everyday palooka.