Complex sentence: Martinez fired on Whitman with his revolver, missing, and McCoy hit Whitman twice with his shotgun, which Martinez took from him, having emptied his own weapon, and fired a final shot at point-blank range.
Split into simpler sentences: Martinez fired on Whitman with his revolver, missing, and McCoy hit Whitman twice with his shotgun. Martinez then took McCoy's shotgun from him, having emptied his own weapon, and fired a final shot into Whitman at point-blank range.