Welcome to the forum. 
My Lee manual puts the .30-40 at approx 38,000 PSI and the 7.62x54R at approx 50,000. I'm sure those are sporting / SAAMI figures. I own several Mosin-Nagants and shoot milsurp ammo. I would venture a guess that Bulgarian "yellow tip" is probably closer to 70,000 PSI judging by the recoil and fireball that erupts from the muzzle.
My Lee manual puts the .30-40 at approx 38,000 PSI and the 7.62x54R at approx 50,000. I'm sure those are sporting / SAAMI figures. I own several Mosin-Nagants and shoot milsurp ammo. I would venture a guess that Bulgarian "yellow tip" is probably closer to 70,000 PSI judging by the recoil and fireball that erupts from the muzzle.
Willie