Need help identifying Diana model air rifle

I have this Diana air rifle I was given. It has no Model # stamped anywhere. Does anybody know what model this would be. Also Is it Carl Bock? Thanks to anybody that can help with information
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Looks to me it likely is a pre-WWII Model 25. Sometimes a date stamp appears on the butt end, or under the barrel visible when cocking. A little info, from Danny Garvin's VintageAirgunsGallery:
https://forum.vintageairgunsgallery.com/pre-war-diana-air-rifles/diana-model-25/

The Karl Bock name would have been a retailer / distributor who contracted Diana to mark guns for them. Google indicates there still may be a "Waffen-Bock Carl Bock GmbH & Co." in Frankfurt. Diana has marked guns with many distributor brandings over the decades (e.g., Hy-Score, Winchester, Beeman).

It seems to be quite well preserved!

Don R.
 
Looks to me it likely is a pre-WWII Model 25. Sometimes a date stamp appears on the butt end, or under the barrel visible when cocking. A little info, from Danny Garvin's VintageAirgunsGallery:
https://forum.vintageairgunsgallery.com/pre-war-diana-air-rifles/diana-model-25/

The Karl Bock name would have been a retailer / distributor who contracted Diana to mark guns for them. Google indicates there still may be a "Waffen-Bock Carl Bock GmbH & Co." in Frankfurt. Diana has marked guns with many distributor brandings over the decades (e.g., Hy-Score, Winchester, Beeman).

It seems to be quite well preserved!

Don R.
That's the closest I found just due to that rear sight blade.. but also I assume the model # was stamped in the butt end ?

But that 23 is a darn good guess imho.