Wiedzmin,
fFrom my readings UK interest in W-Ni-Fe penetrators started around 1979, because of circa 10% advantage in penetration over W-Ni-Cu. W-Ni-Cu, however, could be much easier to obtain by utilizing penetrators from APDS rounds. In 1979 it was said that UK would be ready to introduce new technology (W-Ni-FE) in 1984.
thank you
something about L23A1