[zulu64]

It was common practice in ww2 to knock out tanks by shooting underneath them: the ricochets then pierced the armour from below as tanks weren't very heavily armoured on the bottom.. But this means those ricochets bounce pretty hard.. 8)
I would love to see this in game: in red orechestra eg the ricochets of tracers are fantastic! hock:

What reference to this do you have ?.... sounds like an Old wives tale to me and impractical to use with any consistency.

Ricochet trajectories are affected by so many things that to use it it as a predictable feature seems impossible to me. In addition so much energy is lost on the first ground contact that any real ballistic penetration of a hard skinned target would be lost. Not forgetting HE fuzed ammunition which would most likely detonate on first impact.

Real world studies (which I have based on DEFA 30mm Ball ammo) show typical ricochet trajectories after first impact on various surfaces. Typically the round deflects up to 30 degrees from the pre impact line of flight. This is caused by round rotation that can be as high as 50,000RPM (clockwise in the case of the DEFA). For those rounds that do ricochet the typical climb angle is around twice the impact angle.

In the case of water Ricochets do not occur for impact angles >10 degrees.