Gerry:
Does it have any additional proofmarks like Austrian or Hungarian? I think Romania was being influenced by Hungary about that time and was occupied by the Germans during WWI. I don't know of any Romanian proofmarks from that period but there were arsenals at Cugir(Bucharest/Bucarest)-, Sadu, and possible a few others. But Cugir and Sadu were combined to form RATMIL(Regia Autonoma de Technica Militara) and circa 1964 you begin to see Romanian marks on AK variants. They claim to have been in operation for 200 years -
http://www.arms.home.ro/arms/pg/index.html .
I would say that B.D. Zisman was a firearms merchant, and possibly gunsmith, in Bucharest/Bucarest, Romania.
Kind Regards,
Raimey
rse