If your gonna do it in an apartment, keep it in a seperate room / closet with a very secure lock on it. Not just one of those door nob courtesy type locks, but an actual security type padlock. re-enforce the jam too. Make it so the maintenance staff would have to literally break the wall down to get in. Take all the usual precations like blocking all light, controlling oder etc. Tell no one and don't deal and you will do OK. If anyone like mintenance or visitors asks whats in the locked room, tell em thats where you keep your firearms and amo. Just want to be safe right?

good luck,

bob