Thanks brother.

From the Verney-Carron 1914 catalog

https://en.calameo.com/read/0054478584946e91a2418

[Linked Image from photos.smugmug.com]

Poudre T Pyroxylée Sans Fumé (introduced in 1899) was a 11.5 grains/dram = 34.5 grains = 3 Dr. Eq. powder and was used by the French Proof Houses starting in 1900, and was the only powder used for Nitro proof post-1914.
Standard 12g load for Poudre T was 2.2 grams = 34 grains = 3 Dr. Eq. with 1 1/8 oz. = 7,170 psi + 10 - 14%. Maximum load was 2.6 grams = 40 grains = 3.48 Dr. Eq. with 1 1/4 oz shot at 620 Kg/mm2 = 8,818 psi + 10 - 14%.

It seems likely that Belgian guns proved with French powders were done so at the request of the French dealer.