There's torpedos and miles of empty ocean. Granted, it's not as hands-on as a firing range, but it's more impressive.
To add some spice we could surface, launch Drxav off in a boat and then submerge watching him through the periscope as we fire random torpedo's.
1. If he's a shot zombie then he will start to smell in a few days anyway
2. We can sip tea and have some fun. The leader to blow him up gets half price arms for a year??