In 1964 the Cetme-C rifle was introduced in spanish service, and the 7,62 Nato round started mass production at Toledo and Palencia. All components in these cartridges were spanish made, but the previous year, 1963, some cartridges were loaded with spanish “metal” but belgian powder, while a suitable spanish powder was developed.
The round had a boattail bullet weighing 9,45 g. Both gilding metal and gilding metal clad steel jackets were used. The propellant was a belgian ball powder. Reference: Molina-Orea pages 452-453.
This 1963 cartridge was named “according to Nato standards”, was so identified on the boxes and had a distinctive headstamp (P 7,6 N 63). The “N” stands for Nato, obviously.
I don’t know if a large lot was made, but it seems unlikely because this headstamp is rarely found.