I couldn't find an image of an O/U Charles Daly by Richard Schüler / August Schüler Herkules(1910) action with the stamp of a pick and ore tub in the shape of a foot but I did find a Mahrholdt Hakenloser Herkules Bockgewehr with the stamp on the underside of the lumpless tubes on page 74 of the Double Gun Journal Winter 1998/Vol. 9 Issue 4. I find it difficult to believe that either Richard Mahrholdt of Innsbruck or August Schüler made the examples but sourced them. And the source will reveal the maker behind the stamp.

Kind Regards,

Raimey
rse