What action movie sequence should have killed/ seriously injured someone?

[Bohandas]

The faster the round, the quicker it disintegrates in water. Sub-sonic munitions penetrate just fine into water - the Russians even have a series of rifles that's intended to be used underwater by their frogmen (most recently the ASM-DT amphibious rifle).

My understanding was always that it was the transition from air to water that messed with the bullets moreso than the water itself and that guns in general would fire fine underwater