I'd call the 2 g Sch P mark as two grams of Schultze Pulver, an early smokeless. Two grams comes out to about 30.8 grains, about right for Schultze but not for black.
The problem with separating the two types of powder in German is that both begin with sch: schwartz for black and Schultze for the early smokeless developed by him. Black powder is typically marked in German proofs as S.P.
One dram = 27.34 grains
One gram = 15.4 grains
One dram = 1.78 grams or so
Usual 16 gauge black powder charge is in the range of 2-1/2 drams, which works out to somewhere in the neighborhood of 4,4 grams.
Drams, grams, grains, it's enough to make anybody crazy!
