Back in 1996 I was stationed on a carrier. If you were going to security department, you got to go to an old boat and learn tactics while "playing" paintball. Gun I used were AGD Sydarms as our pistol sim, KP2's as our shotgun sims and AT-4 as our M-16 simulators. It was a blast with the exception of cleaning up every day though.
I don't know if they still do it (haven't heard of it on a while). I know there were talks about stopping it because being in old ships you have the issues with rust, asbestos and lead paint. Asbestos was a huge issue. I get disability when I retire because I'm considered to be exposed to it.