Yes and yes. 54r.net is light on info on Bulgarian ... about all it says is its factory 10. I have a friend nearby with a spam can marked with silver tape and the same year code ... I'll try to get him to open it and post pics of both rounds.Do you have pictures of boxes and individual rds? Did you check 7.62x54r.net?
If you are shooting them at Camp Perry you might sort them by headstamp...if not, no sweat all is good!Awhile back I bought some Bulgarian ammo and one was in boxes and the other was in paper. I dumped them all into an ammo can. Should I be concerned? I did not know their was a difference.