FYI- Don’t try to shoot Hollow Points out of anything under water. Instant barrel plug at the minimum.
Also it’s very likely the Firing Pin will Hydrolock.
Sigh.
Not at all. Water. like air, surrounds the bullet, so there is no “impact” just equalized support from the media- in this case, water not air.
I have fired HST 40 cal , 9mm and 45 acp from several handguns under water with not expansion at all- not enough velocity upon impact nor with the media it is in. Guns cycled normally, fired several repeat shots w/o issue.
ARs under water too- no bullet issues nor much efficiency- water is a great inhibitor.
No signs of high pressure- normal function again through several rounds of commercial, handload and military rounds, BTHPs, Soft point and FMJ.
Shotguns are rather sad underwater-shark guns are contact weapons- so there is not water to contend with....
Regards