I have experience in this area. It was never even a consideration, because there was never a thought given to it. We were
Surface Fleet so to speak
I had friends in a variety of agencies, state, local, county, and federal... none ever carried FMJ for duty. Under any circumstance, that I'm aware of.
If it's a concern, tell yer guys not to shoot till the guns out of the water
Once the gun is out of the water, hydrostatic pressure is zero.