On a kayaking, and camping trip... I do seal loaded magazines and other essentials in a water proof bag, however I am more concerned with an immediate action where I may need to draw the firearm and fire.
There was one occasional where I rolled my kayak when I hooked a musky with an ultra-lite rod while targeting small mouth.
But my bigger concern was wade fishing and having the gun submerged for most of the day.
I have heard of primer sealant, didn't know if there was any certain brand of ammo who did it better, never thought of nail polish however.