Capitol decided to assemble its own library in 1955, and when Nelson Riddle turned down the job of a composer of their musical cues, they hired Loose and John Seely.
Film companies such as National Screen Service and Filmack Studios later placed some of William's cues onto its soundtrack under its snipe works beginning in 1964.
[2] Loose's accomplishments led to invitations to compose scores for American television series such as The Sheriff of Cochise and The Texan.
For several decades starting in the 1950s, Loose's composed music for films and television, including such diverse works as the themes to television series Trackdown (1957-1959) and Wanted: Dead or Alive (1959-1961), the 1966–1981 game show The Hollywood Squares (1969-1979 version of theme music), and films Tarzan and the Great River (1967) and Tarzan and the Jungle Boy (1968) starring Mike Henry, many short pieces for NFL Films, and music for Russ Meyer movies including Cherry, Harry & Raquel!
He also scored many cult 1970s films such as The Rebel Rousers (1970), The Big Bird Cage (1972), The Wrestler (1974), The Swinging Cheerleaders (1974), Devil Times Five (1974), The Grizzly and the Treasure (1975) and Mako: The Jaws of Death (1976).