This is an argentine 12-70 ga. “Mini-granada” (Mini-grenade) cartridge. It was made in the 1970’s by Fábrica Militar “Fray Luis Beltrán” of Fray Luis Beltrán, Santa Fe, Argentina as part of a series of special purpose shotgun ammunition. Several variations were made and this is a factory sectioned example. Aluminium case used was originaly produced for the 12-70 ga. “Propósito General” (PG = General Purpose) buckshot cartridge.
According to some people from the factory all 10,000 rounds produced were ultimately destroyed.
These are some catalog scans showing some information about this cartridge (first from the left):
From Fábrica Militar “Fray Luis Beltrán” c. 1978 catalog (spanish edition):
Designation: Minigranada Explosiva. Brass case.
From Fábrica Militar “Fray Luis Beltrán” c. 1982 catalog (spanish-english edition):
Designation: Proyectil explosivo de Fragmentación “EFRAG”. Aluminium case.