Didnt mean to offend anyone with that response, but I dont think glock would condone/warranty there gun being fired underwater.
And not trying to influnece anyones believes, but with the advent of powerheads mounted onto speargun shafts, why would you subject a $400 handgun to that kind of abuse??
BTW, are you talking about firing the weapon underwater while scuba diving?
Seriously, penetration would be less than 4 feet considering that most water traps to test bullet expansion, etc are not that long
anyway.
Since the glock 17 can have a muzzle vel of over 1350 fps (in air), I would be slightly concerned about the concussion wave from the shot, make that any gun though
Not flamming.....just expressing my opinion....