[ItsMeAshot]

I can’t be sure, I shot this box almost 6 months ago, and I made the post long after. I don’t have any ammo or casing left..

 

[PMB]

I thought you kept the case even though it had a Berdan primer.
Well let's say it was a Polish Mesko surplus ammo which allow to get that 0,46 MOA group at 300 m.