The Prvi Partizan IS nice ammo, & at today's prices, very reasonably priced.
I grabbed all I could find a while back when I found a source selling it for U.S. $9.95 per 20

The HXP was a lucky find, I'm discovering there are little pockets of good ammo out there, but it is no longer the internet mass marketers. This particular supply comes from a mom & pop gunstore located in the basement of a small town general store.

As for the "Z" suffixed ammo I'm utterly confused now as to wether it's a powder change, a bullet change , or both. Luckily I have a couple of crates to open up & I'll pull down a round & see what the heck I just bought.

Personally I load BT bullets as the rifle likes them, & 3031 powder as I like it, so I'm assuming all the rest is foam on the brain internet syndrome, particularly as the illustrations posted contradict themselves, the case headstamp being VII which when I went to school was Roman numerals for "7" but the text referes to "8" which would be VIII??????