This cartridge was produced by CBC of Brazil for the Ejército Nacional de la República Oriental del Uruguay. It bears an special headstamp which was designed in 2008 and delivered in 2009. In 2010 another lot was delivered including 7.62 x 51 mm NATO cartridges with same headstamp style.
Headstamp reads CBC 5,56 L01-09 UY (Lote 01 2009 Uruguay). Bullet is SS109 type.
Ron, now you have another country file!!!