Found a relevant thread
https://doublegunshop.com/forums/ubbthreads.php?ubb=showflat&Number=172878&page=3

The French equivalent to Nitro is "Poudre Pyroxylée".

The 1900 Manufacture Française d'Armes de St Etienne listed J, S, R, M, & T powders

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Poudre J and Poudre S were both used as proof powders from 1896-1914.
Poudre M 1898-1914.
Smokeless Poudre T was used by the Proof House starting in 1900, and was the only powder used for Nitro proof post-1914.
There was also a Poudre T Bis (two)
https://books.google.com/books?id=dIdBAAAAIAAJ&pg=PA87

Courtesy of JayCee
1920 levels of Preliminary Proof for finished and joined barrels:

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12g
-First proof: 11 grams of BPnº2 and 70 grams of nº8 shot for 941 kg/cm2 = 13,384 psi
-Finished barrels: 10 grams BPnº2 and 60 grams of nº8 shot for 791 kg/cm2 = 11,250 psi
-Superior proof: 14.5 grams BPnº2 and 75 grams of nº8 shot for 1133 kg/cm2 = 16,115 psi
-Double proof: 20 grams BPnº2 and 120 grams of nº8 shot for 1441 kg/cm2 = 20,500 psi
-Triple proof: 30 grams BPnº2 and 180 grams of nº8 shot for 1726 kg/cm2 = 24,550 psi
The BPnº2 is called in French "Poudre Noire Forte Nº2.

These numbers are different; from https://www.shotguns.se/html/france.html
14,223 psi = 1000 Kg/mm2 Provisional Proof
16,356 psi = 1150 Kg/mm2 Reinforced Proof
17,779 psi = 1250 Kg/mm2 Double Proof

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and https://doublegunshop.com/forums/ubbthreads.php?ubb=showflat&Number=609519&page=8

https://sites.google.com/a/damascusknowledge.com/www/home