This time a CZ52. Typical refurb CZ52. Matching serial numbers slide, barrel and frame. Firearm manufactured in 1953, refurb mark is VOP 91. Chambered in 7.62x25 Tokarev. The ergonomics are horribly bad.
You are correct regarding the firing pin. Harrington Products is the company that supplies 3 different types of firing pins for the CZ52, as well as hardened rollers, a different extractor, and even a take-down tool. Plenty of parts out there, too.
It is a good, solid firearm, and the Czechs only improved their designs over time. The CZ52 is the easiest handgun I have come across to field strip - just pull down the tabs in front part of the trigger guard and lift off the slide. Even easier than the P64 (another firearm I have a lot of time for). I'll probably be putting this one up for sale, as building up your own business costs too much bloody money lol.
I remember when these first came into USA, The gun show had crates piled high selling for $99. each & ammo was 9 cents a round. Most of them were sold quick. Once ammo dried up they started appearing on secondary market.