Well, in all cases, the surplus ammo is most of times a surprise , specially the ones as old as the 1950s . Those have very hard primers and has many misfires because of it. In my experience , the ones that I had problems with were the polish from the 1950s and the romanian ammo from 1983 . Those gave me problems. Now, I have been shooting Prvi Partisan from the 1986 , and even from the 1960s , and so far , it is perfect. So, I decided that from now on I will only use Privi Partisan surplus 7.62x25 . Perhaps you got a good case of ammo , but be careful and go slow and check it well .