I have lots of the Bulgarian as well - just seem to have a ton of split cases when I fire it out of any of my M-27, M-28, M-38’s, M39’s, M-44’s, 91/59’s, or 91/30’s :-)
And to the other poster referencing the website...
7.62x54r.net - anything and everything about Mosin’s.
Buy it cheap stack it deep.