The irreplaceable guns are probably better off in a more secure location. If nothing else, well oiled, vacuum sealed and put into a bank safe deposit box and insured.
Short of a real safe, all you can do is slow down a determined thief. Even the "residential security containers" (aka "safes") can't stop thieves with tools and plenty of time.
You can buy a $99 strong box safe that'll hold 2-4 handguns and mount that to a closet wall.
¹ Placing it on the floor is possible, though filling the lower portion with bags of lead shot will make it difficult to just carry off.
²
Mossberg had a wall-mounted shotgun lock that enclosed the shotgun action with a lower-end mount that the muzzle rested on. Or simply eyebolts screwed in to the studs with extra-thick vinyl-coated cable padlocking the long guns individually will slow them down.
Your best bet it to layer your security as much as you can. That starts with a peep hole in your front door and a bright porch/entry light. Making sure your windows are all secure against opening from the outside is next. Spend the extra money for a deadbolt lock on the door. Be sure it's anchored with at least 3.5" screws to the door jamb.
Alarm systems aren't practical in most apartments. There are are some "portable" Laser/IR/Ultrasonic types that will scream loudly however. These are placed in a room and emit signals that cover the room. Anyone interrupting the signals sets off the loud alarm. Not effective if you have pets and/or leave windows partially open and the drapes blow around.
You can buy inexpensive alarms for windows & doors from
First-Alert. These battery units emit an alarm noise to alert anyone inside that a door/window was opened. All a thief will know is that an alarm has sounded. Couple that with a 2nd, much louder unit with a 10 second delay and the noise is likely to make him retreat.
Local alarms (like those above) depend on someone hearing it and calling police or investigating. The noise attracts attention. But if thieves can locate the alarms and neutralize them quickly, it may only serve to delay them a couple of minutes.
Other simple "wireless" alarm systems that come with 24/7 monitoring may be an option, though painful to the budget. A system like
LaserShield has the benefit of portability and 24/7 monitoring. In this case, when the alarm activates, someone can call the police for you.
Now that we've covered the outside, what about inside?
Look for apartments with walk-in closets with a single door. Sliding double doors on closets can't be secured. Adding a simple keyed doorknob set to a walk-in closet door will reduce casual entry. It won't stop lockpicking or lock bumping, nor stop a hard kick. But it's another alarm point and another barrier to overcome.
Advice: Thieves know where to look for "hiding places". They will look under beds, behind pictures & dressers. If they dump drawers out, they'll look under the bottom drawer of your dresser. They'll look in bathroom cabinets, behind the sofa and under it's cushions. Anything they find that
might hold something valuable, they'll try to open - footlockers, cedar chests, plastic containers, etc.
If you try to hide them, it's likely a thief with no reason to hurry will find them. That's your goal -- if they get in, give them a reason to leave in a hurry such as a loud alarm system.
Lastly, a steel gun cabinet is better than nothing, but it can be a false sense of security. The simple types sold by
Homak and
Stack On can be defeated with simple tools.
Home Depot sells a
Sentry brand safe that's small and will hold 4-6 long guns for a good price. Not too heavy either.
¹ If studs aren't conveniently placed, you can screw a 1x2 strip along the wall to help anchor it, along with a 2x2 strip underneath to support the weight.
² On the floor has advantages. A single lag screw through the back into a stud, coupled with 30-lbs of shot in the bottom make it difficult to move. Once pried off the wall, he now has 40-50 lbs to carry.