Dug this up a couple of days ago.
Only a couple of inches deep, but laying horizontal, so it would take forever to sink!
The headstamp has I.M.P.A.
1946
And a faint number 8
I tried to look it up, but I am failing!
Obviously a bad primer.
Per wikipedia -> IMPA Industrias Metal?rgicas y Pl?sticas Argentina ("Metallurgical and Plastic Industries of Argentina") (1928–Present) - barrio de Almagro, Buenos Aires, Argentina. The co-operative briefly made cartridge cases for the military.
Military surplus ammo has been imported into a lot countries to include the US or North America. I have several cases of milsurp ammo from South America, Eastern Europe, some even from the Middle East.
Surplus military ammo and weapons were a cheap alternative to NEW made weapons and ammo for years and were used by North Americans to put meat on their tables.