SNIP Agree that we need to know the terms and length of the existing lease.
I was the victim of such a tactic by a large property manager on two occasions. Not about guns, but other stuff.
On one occasion, they sent a letter saying they were requiring all residents to re-sign their leases instead of converting to month-to-month at the end of the lease. My thought: "Uh...no. All you can do is cancel the month-to-month lease. You cannot require me to sign a new one."
On another occasion, they demanded mid-lease that all residents obtain renter's insurance. Of course, in the body of the letter was the little requirement that the renter name the property owner as an additional insured. My thought: "Uh...no. In fact, the already signed lease expressly said renter's insurance was not required but was strongly recommended. So, where do you get the idea you can unilaterally change the terms of a lease (contract)?"
I ignored them both times. On the first issue, they quit trying. On the second, they kept sending out the renter's insurance demand. I kept ignoring them. Until they actually threatened to not extend the lease for another year. Then I bought renters insurance, but only when they finally exercised a right they actually possessed.
I would never have believed a professional property management company would try such tactics. Then I saw it with my own eyes.