I read a "4" too. Up to 1918 it was 1-Ferlach, 2-Prague, 3-Weipert, 4-Vienna. After 1918 in Austria, one-headed eagle holding hammer and siccle, it was 1-Ferlach, 2-Vienna. In new-founded Czechoslovakia, Czech lion, it was 1-Prague, 2-Vejprty.
Weipert even met a worse fate than Zella-Mehlis, Suhl, St.Etienne or Birmingham: In those former gunmaking centers at least a few gunmakers are left and there are still people to remember the old times. Not so in Weipert/Vejprty: The entire population has been changed in 1945, and what was left of gunmaking was swallowed up by socialism and government agencies like Lovena. I doubt that the Weipert proofhouse files are available through Austria: In 1918 the Weipert proofhouse was taken over by Czechoslovakia as a running concern without a change of persons. 1945 Vejprty disappeared behind the iron courtain, the people who ran the proofhouse were gone. How can local Weipert files be found outside of Czech archives?