I have dug up some more stuff.
Youtube Links:
More useful sources, if you can find them, might be:
Haag, L.C., "Bullet Ricochet from Water," AFTE Journal, Vol. 11, No. 3, July 1979, pp. 27-34.
Nennstiel, R., "Study of Bullet Ricochet on a Water Surface," AFTE Journal, Vol. 16, No. 3, July 1984, pp. 88-93.
The effects of differing water depths on bullet ricochet angles By Erika Chen
"Outdoors in Illinois‎
Illinois. Dept. of Conservation"
Makes an unverified claim that
"Bullets will ricochet from water up to an angle of about 11 degrees and at 15
degrees will not.", but it is not a scientific paper.