Twin bill of dark frontier dramas opens with "Rimfire," which intertwines the stories of a gambler hanged for a crime he didn't commit and an undercover agent searching for stolen gold. James Millican, Mary Beth Hughes, Reed Hadley, and Henry Hull star. And, a Cavalry unit trying to intercept Custer's forces and warn them of the awaiting Sioux ambush are being killed one by one by an unseen enemy, in "Little Big Horn." Lloyd Bridges, John Ireland, Jim Davis, Hugh O'Brian star. 150 min. total. Standard; Soundtrack: English Dolby Digital mono.