This questions seems better in the machine gun section as it is lost on those who only use rifles

Of the surplus lots of ammunition now in the United States does anyone know which makes, year of production, and lots feed reliably in a full auto PKM 7.62 x 54R gun?

Has anyone tested a lot for range, accuracy and penetration in the specific Eastern Standard model lot designation (ie a properly military combat serviceable test?)

Any ideas or insight would be appreciated. We use small lots of surplus for linking in our new production PKM links and we are looking for smaller lots, as it usually is not viable to bring in enough of our new production brass cases boxer primed ball ammunition in with out loosing money. It is good to have a small scale alternate supply. Most/many lots of 7.62 x 54R surplus ammunition which is usually bought on price alone for the civilian market are know to fail in a PKM, let alone being able to pass a proper Eastern Standard military combat service test