Found some brass cased 5.56mm 55 grain FMJ ammo that I forgot I had.

I've had it for roughly 11 years and don't know what it is.

I don't know squat about headstamps or methods of crimping primers, so I will describe and try to illustrate what it looks like.

The primer has three small indentions around it's perimeter at 12, 5, and 8 o'clock .

There is the number 87 above the primer, and 13 below the primer.

Looks kinda like this:
   
          87
           .
         .O.
          13


Any ideas? Would like to know what it is before I shoot it.

Thanks

Quoted: South African M1A3 made in 1987.  Berdan-primed (non-reloadable), hot, 5.56-pressure M193-class ammo.  Good stuff. -Troy

Thanks Troy!