Outstanding French developments of the time are:
-smokeless powder by Paul Vieille 1884; he was succesful, because he tackled the problem using what we call scientific approach today. If you read Duttenhofer created it about the same time, that is far from the truth. Duttenhofer did not have the slightest idea and stuck to black powder technology.
-modern aerodynamic bullet shape 1898: slender ogive (about 10 diameters) and boattail; by systematic trials of shapes A through E, shape D was adopted as balle D. (before you ask: how the other shapes looked like is unknown today; D is not named after Désaleux). Due to French secrecy, the German S bullet got the credits that in reality belong to balle D.
-creation of a drag law (1898) by the (naval artillery!) commission of Gâvre that in the small arms field is still used today under the name G1.
I think you should also look up the 75 mm field gun. I believe it was the first recoiling type (quick fire in British parlance) so that the carriage did not hop around on each shot, but this is not my area. The Americans adopted it, too, I think.
The French also had weaknesses, of course. One is too much emphasis on theory as an end in itself. The books of P. Charbonnier on ballistics are a case in point.
Thinking of the Americans calling Belgian pommes frites “French Fries”, I take the liberty to mention that the le Boulengé chronograph so often used in ballistics, was invented by a Belgian in 1864, not a Frenchman.