Have you taken a look at the various artillery manuals of the period? There are quite a few of them, most of the French, and you can find some on Google Books for download.

Artillery rounds are affected by muzzle velocity, elevation at which the piece is fired, and/or the elevation of the gun tube itself, the condition of the ground, the powder charge and caliber of the piece, weather conditions, among other things.

The following excerpt is from American Artillerist's Companion by Louis de Tousard, Volume II, pages 238-241, and is one of the best artillery manuals of the period:

'...the causes which produce or modify the ricochets of balls...are, first, the mass, the bulk, the configuration, velocity, elasticity of the projectiles: secondly, the direction and height of their fall: thirdly, the resistence and elasticity of the plane which is struck: fourthly, the movement of rotation which they acquire from touching the plane.'

'Ricochet firing is not then confined to any particular charge or elevation: each must vary according to the distance and difference of level of the object to be fired at, and particularly of the spot on which it is intended the shot shall make the first bound. For instance, let us suppose a battery firing a ricochet, under an angle of ten degrees, upon a half moon, with a small charge; if it were wished to fire from the same battery upon a more distant work, the charge should be increased and the angle lessened. If this work should be at the same time of an extraordinary height, then both the charge and angle should be increased; but if it should be lower, no doubt but the angle should be diminished, and the charge increased.'

'Then, by varying the charges and angles, it is possible to fire longer distances, and carry the shot over greater heights than it is customary to do; for in the same circumstances, with the same angle and height of fall which commonly produce ricochet, the shot will certainly ricochet the same, everything being equal besides...'

If you would like a listing of appropriate artillery manuals, I would be more than happy to supply them to you, either on this forum or by email.