The vz. 24 is most commonly found from that early batch and the next few years, and from another batch made as tension ramped up in Europe, just before the change to the vz. 38. It is basically identical to the earlier vz. 22 except with less hand fitting (and therefore, more attention to interchangeable parts) and more stamped parts.
Berger's book is very good, but dated and out of print; copies cost as much as some of the pistols. (I'm working on a book on Czech and Czechoslovak pistols that will be more comprehensive, and available as an e-book). Ed Buffaloe's Unblinking Eye website is excellent on early Czechoslovak pistols. Here's his vz.24 page.
http://unblinkingeye.com/Guns/VZ24/vz24.htmlvz. 24 grips are ugly even when they're in perfect shape, compared to the checkered one on the vz. 22. But that's the way they made 'em.
Be aware that replacing the original grip (or original anything else) on a vz. 24, or any other collector pistol, has the potential of diminishing its collector value. If you want a set of nicer, newer grips, that's fine (it's your gun after all), but you'd be well advised to keep the old grips with it, for your benefit or that of your heirs when it's time for it to go.
Buffaloe notes that early vz.24s may have the checkered grip of the vz.22. Yours has a doubtless original smooth grip, and Czech-language sources seem to list it as one of the changes. The checkering came from the pistol's ancestry as a Josef Nickl Mauser design based on the 1914 7.65 mm (which was based on the 1910). He did this exact gun as a 9 x 19 mm service pistol for Mauser in 1916, but Mauser passed on it, and he scaled it down for the Czechoslovak requirement when he was assisting them in getting CZ running as a rifle factory using Mauser tooling. Nickl made dozens of prototypes for Mauser, where he worked for decades, but his most produced firearm is that vz. 24!
The unusual two-switch safety (one applies it, and one with a different motion releases it) came from Mauser, and was originally on a 1906 prototype of a pistol with magazine in front of the trigger, meant to replace the C96 Broomhandle. Nickl may have worked on that design alongside other Mauser craftsmen and engineers. (At the Mauser-werke, unlike many other gun manufacturers, everything was a team effort and they weren't much into individual credit).
Your pistol may be unit marked, usually on the foregrip. It may not be. (I have one with no marks, and one with
two unit marks, one crossed out!) The Buffaloe link explains how to read the marks; the code letters most often seen are P for Infantry, or D for artillery. I believe (without looking at my references) that this was a list from Austro-Hungarian practice, just with Czech rather than German language abbreviations.
The mark on yours is interesting with CZ (up arrow) 25. This is an acceptance mark of some kind. More commonly these are seen with a military acceptance mark or a proof mark (seldom both on the same gun, but it happens, as when a gun was disposed by the military and re-proofed for civilian sale). Buffaloe shows the military mark, the Czech two-tailed lion and year. Some vz.24 rifles made at the same time have a large version of the lion on the receiver ring (earlier vz.22 rifles just say "Czechoslovak State Armory, Brno" on the receiver ring in Czech).
The civilian proof marks of that time would have been year, symbol, sequence number, following Austro-Hungarian practice.
Your pistol should be marked "Czech Armory Inc. in Prague" in Czech on the sight rib, and even on one as early as yours it should have a double-tailed lion there. I'd be interested in hearing if it doesn't; it may have been a private sale gun, as military and police guns all were supposed to get the lion. (The guns were made in Brno, but company HQ was in Prague. The marking usually but not always kept saying Prague even when guns were made, later, in Strakonice).
