True, but a classic Fender P is clearly not the worst choice for metal.I believe round wounds were available as early as the mid 60s. I have never read anything where Geezer said he used flats, only that his strings were probably dead when recording because they didn't have the money for new strings.
If the bass was stripped, who knows what color it started as.
The larger point is that people fixate on Geezer using a "classic" Fender P, when he hasn't used one for the majority of his recording or touring since roughly 1972.

