I've not found published German proof house proof and service pressures but they were very likely the same as those of the Belgian proof house. After the proof house revisions of 1924, the Certificat d’epreuve specified:
“The pressure developed, measured by crusher type device, lower or equal to 600 kg per square centimeter for sizes 16, l2, 10, 8 & 4; 670 kg per square cm for sizes 20, 24 and smaller.”
600 kg/cm2 = 8534 psi maximum SERVICE pressure;
670 kg/cm2 = 9530 psi maximum SERVICE pressure
+ 10 - 14% by piezoelectric transducer measurement
20 g was PROVED at 1000 kg/cm2 = 14,223 psi
12g PROVED at 900 kg/cm2 = 12,801 psi
Modern transducer numbers for 20g would be close to 15,500 psi; 12g about 14,000 psi
