1) Storing them in the base armory
2) Attending a shooting competition
3) Transporting them to a (Navy) housing unit (where you have to lock them up anyway)
There is more amplifying information in the actual instruction, but this is it in a nutshell. The base security officer (here anyway) has an application process to allow you to get a weapons transport pass, that allows you to bring the weapon on base ONLY for the above reasons. Even if you have the gun and the ammo locked in separate containers, out of reach of the driver (Federal Transport regulation), you still can be stopped, and your personal firearm confiscated, and you will be prosecuted. For military folks, this will be disobeying a direct order (Instruction), for civilians, I'm not sure how that process works.
I think it is really unfair (ridiculous) that we are trained to use firearms under battlefield conditions, however, not trustworthy enough to use them to protect ourselves and family on our "homeland battlefield."