2.9 Grams makes a lot more sense than 29 Grams. On a very poor condition 16/16/8x58Sauer drilling I have proofed 1907 the shot bbls are marked 2Gr Sch. P. / 28.3Gr Bl with a crown/N mark.
I cannnot verify the accuracy but did read some time back from a sourse I though reliable at the time that German proof laws prior to 1912 required a shot bbl to be proofed wit a load of double the amt of powder specified for the service load. This it was stated was the reason so many pre 1912 German guns carried no nitro proof & those which did most often had a very light service load marked on them. This is compatable with my bbls.
However doubling 2.9Gr gives 5.8Grs of Schultz or about 89˝ grains which = 6.4 Drams Equivelent.This is still one Whopping Big load of Schultz in a 16ga even for a proof load.
Doubling the 2Grs as on my bbls would ebd up with about a 4.4 Dram Equivelent proof load, still quite stout aplenty.
