Where and how to buy choke for zabala shotgun?

We suggest speaking with a gunsmith, as you will most likely need his help installing it. He can give you suggestions based on the kinds of modification you might want to make. For example, if the barrel is other than cylinder bore, it will need to be cut off behind the choked portion. This should be done by a professional, and the choke assembly should be sweated on and silver-soldered or otherwise secured. If there is a rib on the barrel, it becomes more complicated yet.