I would like to add to the piece on the 155mm Schneider C15S and C17S field howitzers that the C15S had a swinging loading trough attached to the left side of the cradle. This was a feature that the later C17S lacked. Instead it used a removable loading tray that could be placed on the cradle when loading. Of course the later model had a de Bange pressed asbestos obturation pad on the face of the breech screw for use with bagged charges instead of using brass cases for obturation. Post war Soviet artillery designs (ie: the 122mm M-30 (M-1938) field howitzer, the 122mm A-19 corps gun (M-1931 and M-1931/37) and the 152mm ML-20 gun/howitzer (M-1910/34 and M-1937) all used a Schneider type breech modeled on those of the 105mm L13S field gun (in Russia this was the 107mm M-1910 field gun) and 155mm C15S (or should I say rather, upon the earlier Schneider 152mm M-1910 field howitzer), with separately loading cased ammunition.
One note about French artillery terminology: the adjectives short ("court") and "long" are used in their masculine form, not in the feminine form "courte" or "longue", because "canon" and "matériel" are both masculine nouns. Example: The Schneider 155mm L17S field gun was called in its French long form "Matériel (Canon) de 155mm long modèle 1917". Same rules would apply to the GPF: "Canon de 155mm long Grande Puissance Filloux" (the word "puissance" is feminine, however careless anglo-phone writers, and in this Ian V. Hogg is particularly guilty, transform it into a masculine noun by using "Grand" instead. They [ie: Hogg, Gander et al.] are prone to carelessness elsewhere as well, not just in nomenclature. Horrors!... I think I just gored a sacred cow or two; you can't do that, it's just not done!)