Welcome to Bersa Talk oldgrunt, I do believe magazines for your model 223 will interchange with those for model 644/622. You can find information on each of these models here http://bersachapterhouse.50webs.com/family.html.
Look here for possible magazine dealers http://www.triplek.com/Pages/Magazines/index.cfm/gun_magazine_detail/647
http://www.hoosiergunworks.com/catalog/magazine_pistol.html#pistol
http://www.ammoclip.com/B/bersa_644_622.htm.
Hope this is helpful. regards jab
(Long story short - pollyb is a long standing handle, jab is a male.)