I have a like-new Yugo Model 48 Mauser in 8 MM that I have enjoyed shooting for the last 3 years, and previously owned a Spanish Model 44 airforce rifle for 20 years. Here is what I found in the ammo department.
As far as surplus ammo goes at this time, the Turkish stuff has been very accurate in my Yugo, most of the time the cases are fine, all 100 % sure fire. I have had some batches that had primer bursts, 1931 vintage, and some 1947 vintage with lots of neck splits. The stuff in the blue ammo slings would rub on my bolt face, indicating my tight action of the Yugo so I only buy the green (olive) colored sling ammo.
The Yugoslavian surplus was ok in accuracy, I will never buy another box as the frequency of primer area leaks onto the bolt face was really bad! I used some Italian/Egyption contract ammo, so-so accuracy, all sure fire. German army late war, (dated Feb. 1945) ok stuff, a few of the steel cases would stick in the chamber due to the lacquered coating.
Venezuelan surplus had a lot of dead primers, (hang fires) not worth buying unless super cheap. I clean immediately with black powder cleaner, and then Hoppes #9 for the corrosive primers. One benefit of Turkish ammo that I have enjoyed is that they are already on the stripper clip, and dust free, you can load and fire quickly, getting the experience of what it was like to shoot a gun like this in battle. I let the gun cool down after 10-15 rounds, but to shoot commercial ammo quickly would cost a few bucks! The Turkish ammo uses cupro-nickel bullet jacketing, a harder material than the copper, but does not fowl the bore.
I am now to the point where I am buying the commercial ammo, and will eventually handload. I use Sellier and Bellot all the time in my other guns, good stuff. Will get a box soon for the ol' Mauser.
In summary, the surplus is cheaper, but you need to clean it, and some of it splits or has dead primers. All in all, I have been satisfied with the surplus.