Could a BC-304 manufacture more railgun ammunition from metallic asteroids?
Short answerYes, if it carries the right production equipment, but fighter cover would be needed while the ship handles and processes the asteroid.
NotesA commenter suggests using metallic asteroids as raw material for railgun ammunition when the ship has onboard production facilities. The answer agrees that local resources could replenish simple inert projectiles without returning to a distant base. The operation is not instantaneous: the ship must locate, handle, and refine an asteroid while its attention and maneuvering freedom are constrained. Fighters therefore remain necessary to protect the vessel during the replenishment work.