In 1846 Georg Lindner was listed as a "Gewehrfabrik"; therefore, he had to have apprenticed/worked for, or was working for, a "Gewehrfabrik" owner and at the time they were:
Gustav Gottlieb Haenel
Johann Paul Sauer
Valentin Christop Schilling
Ferdinand Spangenberg
Heinrich Sturm .
There may have been another or 2 I have missed but for now I would venture a guess that Georg Lindner apprenticed at either Sauer or Schilling.

Kind Regards,

Raimey
rse