I believe that SchP refers to Schultz Powder (Bulk Smokeless) & the 29 would be grains. Schultz was know as a 42 grain powder, meaning 42 grains was a 3 dram equivelent of it. This load could be dipped with a 3 dram Black Powder measure. 29 grains would thus be approximately a 2 dram equivelent load.
The 118.35 "Gauge" of the bore indicates it would accept a plug Gage having a .340" diameter but not a 108.49ga (.350") diameter plug gage. The Gauge size markings for rifle bores were discontinued in Germany with the 1912 rules of proof.
Prior to 1912 I understand German rules of proof required the same % of overload regardless of powder type. This resulted in a very excessive load for smokeless powders, so those makers who chose to have the optional Smokeless proof applied most often specified an underload as the standard, thus the 2DE with a fulll ounce of shot.
"IF" this 29 SchP referred to grams of black powder this would be slightly in excess of 1oz or 16 Drams of powder.
