I find the CZ P.22, the CZ P.24, the CZ P.27, and the CZ P.38, but not the CZ P.28.

About the CZ 1927, my resource says: "...[M]arked the same as the CZ 1924, but the cocking grooves on the slide are cut vertically instead of sloped as on the earlier model."

Might you have a CZ P.24, made in 1938 (the last year of production)?
The problem with that, though, is that the P.24 was in 9mm Short (.380 ACP).

It seems that you have a nice little puzzle on your hands!

no model 28 listed anywhere i can find

Very interesting puzzle indeed, took a look in my reference materials and see no mention of a model 28 by CZ.

Also entered this query with a photo on thefirearms forum under Centrefire Pistols & Revolvers. Had one reply saying very rare & made only in Yugoslavia. Tried to enter pic on this forum but it didnt work.Im not upto knowing what to enter as a URL,Sorry about that,but Ive a lot more to learn as yet.

Additional info on CZ 28,top of slide reads CESKA ZBROJOVKA AS v PRAZE 4591 if that helps with ID

so you have a cz 28 marked as being made in the CZ Prague factory and the guy from the other forum says its a very rare YUGO made pistol..... sounds like he has the answers for you because from what i have read here, no one can find out ANY information on the gun, even the existence of the model number.

just on a side note ANY gun made in the CZ Prague factory in Yugoslavia would be the rarest of rare .

Just a thought: Is the number "28" associated in any way with a stamp which looks like a spread eagle standing atop a circle?

The Pic I was able to show on the other forum shows the 28 on the rear L/H slide, below that, just above the safety is C <--<<<<<Z 4591. the arrows are vertical not horizontal as Im not able to print them correctly.There is also C arrows Z in front of the 28.On the R/T side there is a very small C arrow Z at the rear of the frame. a no 29 in front of the stripping bolt,and at the top of the trigger guard is a what looks like an upstanding bear with outstreached arms and possibly wings on its back. Regret thats all I can relate, I`m as puzzled as everyone else,I certainly dont think its a forgery as why would anyone waste their time on something thats not that valuable to start with.

Additional info. on L/H side under slide groves is C vertical arrow Z in front of the 28. Same markings just above safety catch,but s/n 4591 instead of no 28. Large N & P combined into one letter with a small p sitting under the large P. On the R/T side at the rear of the frame is a small c arrow z. the no 29 just in front of the stripping bolt recess,and what looks like an upstanding bear with its arms out and possibly wings on its back ? at the top of the trigger guard.Have you been able to check out the photo info on the other forum ? sorry I cant include it here but the proceedure is different.

Upload your pictures to Photobucket, and then post the links to them in this thread.

The only CZ logo with which I'm familiar is the one used from the 1960s through (I think) today: The "Z" sits within the "C". That is probably the wrong one anyway.