This box was originally named “Caliber 223” but was later rubber-stamped “5.56MM”. It belongs to a lot of several thousand rounds shipped to Spain, where the CETME was starting trials with rifles in this caliber. CETME is known to have loaded also 5’56 mm ammunition with components furnished by the Toledo factory.
The cartridges in these boxes bear the current R A headstamp, and the also current pinkish-purpleish primer seal, smeared all over the case head.
CETME stands for Centro de Estudios T