I bought 2 CZ-52`s but not at the same time couple years apart. The surplus ammo is nasty to shoot. This ammo was for the sub machine gun. I can`t remember the model of the sub machine gun. That 86gr bullet is running at speeds near 1600fps. I made reloads and reduced the load to where it was just enough to work the slide. 110gr RNFMJ (M1 carbine bullet) and 4gr 700X. I also used lead same weight. Seem to tame it down. I converted the other one to 9mm Lugar, works great. The 9 was a little finicky with some of the factory loads. It works great with the Win 115gr fmj 9mm. Happy shooting with your new toy.