Sue them. Call the NRA. Call your lawyer. Have your lawyer send them a letter on NRA stationary. From DC to Chicago, these unconstitutional pinko carpetbagger landlords are being told by our courts that they can't do this. A total ban on arms in your home is unconstitutional. If they see the NRA stationary, they'll get scared because they know that the NRA has a bottomless legal fund and they don't have a bottomless legal defense fund. They have a budget. The letter doesn't have to say that it's from the NRA. You don't have to lie. The letter on NRA stationary just implies that it's from the NRA, but it's from your lawyer. If you have prepaid legal, the letter is free. If you don't, it shouldn't cost more than $200 and the consultation should be free, if referred by the lawyer referral service.
Good luck and God bless,
P.S. you might want to move into a house with roommates. That will be cheaper than living in an apartment. Apartments are commonly owned by corporations run in New York by carpetbagger pinko liberals. However, if you rent a house, it is often owned by an old retiree like yourself who is living off the rent to fund their retirement. Just ask the owner what he/she thinks of the 2nd amendment and they will tell you. That way, you won't be surprised by a change in the gun policy later.