Like most small guitar companies, they used whatever was available at the time. In 1974, Larry Dimarzio was just getting started (he had his first booth at NAMM in 1975). There were no aftermarket pickup companies for the little startups like BC Rich and Hamer (who both started up with custom electrics in 1973/74). Hamer had to use old Gibson pickups for their first few guitars until early 1975 when Larry Dimarzio started winding pickups for them. Most parts for BCR and Hamer were sourced from existing guitar companies since that was the only option.