I have a 7.62 x 51 with headstamp “RG 71 L2A2 (NATO MARK)”. It has a ringed in primer with a purple PA.
The primer is some type of aluminum looking metal (not shiny). In the center of the primer is a black dot of paint.
The round is filled with what sounds like lead shot so it rattles when you shake it. Brass case with a GM Ball bullet.
What is the proper nomenclature for this round and what is it’s purpose.