Securing weapons in an apartment complex

[Sunray]

"...if the floor is concrete..." It is. Keeps the neighbour's fire out of your unit.
My safe fits nicely into a closet. Hidden and too much trouble to get at and move. Mind you, if criminals can get into your unit, you need to talk to the landlord about the building security.

 

[Ivy Mike]

concrete floors aren't a problem. Tap-cons were created for just such a task.
When its time to move, just take the tap-cons out and fill the holes with some epoxy.
A few small cuts in carpet won't be noticed, especially if they replace the carpet after you move out.

 

[ilbob]

and has those circular keys that are listed as not to be duplicated.

many circular key locks can be defeated with a pen.

and it is easy to get a key labeled "do not duplicate" duplicated. just put a sticker over the side that says "do not duplicate" and write "garage" on it and go to the hardware store.

there are some special cylinders made these days that the keys are much harder to get duplicated because the blanks and cylinders are very tightly controlled and only sold to locksmiths. of course they are much more expensive than a standard cylinder and keys for that reason.