Sorry, I can't be much of a help, but the beer for the Oktoberfest is made for it exclusively. Only breweries that are located in munich may brew the beer and serve it at the Oktoberfest
Augustiner (6 %): Augustiner-Festhalle, Fischer-Vroni (im Holzfass!)
Löwenbräu (6,1 %): Löwenbräu Festzelt, Schützenfestzelt
Hofbräu (6,3 %): Hofbräuzelt
Paulaner (6 %): Paulanerbräu (Winzerer Fähndl), Armbrustschützenzelt, Käfers Wiesnschänke, Nymphenburg Wein- und Sektzelt (nur Weißbier!)
Spaten-Franziskanerbräu (5,9 %): Schottenhamel, Hippodrom, Spatenbräu Festhalle und Ochsenbraterei
Hacker-Pschorr (5,8 %): Hackerbräu-Festhalle, Pschorrbräu Festhalle "Bräurosl"
http://www.muenchen.de/Tourismus/Oktoberfest/z_Bier/172713/01oktoberfestbier.html
Only these can be served. For what you said it's not the Hofbräu , Löwenbräu ( too big, not a small establishment).
Not sure about the other ones, but gotta be one of them.