SHAME on you!
That is INDEED an S-20 variation. (Just funnin!)
The ZVP looks similar, but is way more "Agricurtial". The sights are semi-fixed (Hammer-tap both F/R for windage...) and the Rear elevates via a setscrew. The Velocity of the ZVP hovers between 370 and 410 depending on mainspring and seal condition. (Mine, with a fresh Slavia TEX Model-3 mainspring does 400+ with Hobbies).
The ZVP is quite a bit smoother functioning due to the lower power level and is capable of suprising preformance at 25 yards in spite of the more rudimentary sights. The CZ ZVP's Luger-like Wooden gripframe like the S-20, fcomfortablly fits nearly all hands and balances well.
The BSF S-20 has an adjustable trigger (acessed with a setscrew at the piston's Breech/endcap and the BSF barrel is slightlly longer. The BSF sights are very well made and actually finelly adjustable considering the period in which the Pistol was manufactured. It's power level usually approached 450fps (In .177, I don't know if any .22 caliber was ever made?). Due to the higher power cocking was harder and firing manners were more pronounced than it's Czech compeditor.
Both Pistols shared the marketplace initally, but the S-20 outlived the ZVP. CZ opted to refine the ZVP and morphed it into the TEX Models. Production of the CZ TEX ceased with the Model-3. The Factory refused to further modify the design to include a Manual Safety and the CZ's importation here to the USA ended when stockpiles of the model ran out.
The fate of the S-20 was far different. It's demise occured with the aquisitions, absourbtions, and the sale of BSF lines to it's Geaman compeditor. The very Accurate, dependable, and powerfull S-20 Pistol likewise dissapeared as inventories were sold off. As evidenced above, there ARE a number still popping up on the used market from time to time.
Do shoot and enjoy this fine old pistol of yours!
Your old buddy,
ZVP ( aka: Dave N.)