My dad has Alzheimer’s, his belongings are at my home. My brother want his things. Do I have to turn them over?

If you decide to sells the firearms or anything else I would have them checked for value as some might be worth more than you think. Like my Mothers candy dish set. Valued at over 600 dollars.

You might consider after dad is gone a transaction. Have the things appraised and offer them to brother at a profit to yourself for your trouble plus the shipping fee.... unless you want them yourself.
Your dad would probably like him to have them.

Use your Dad's money along with the money that you get from the sale of the guns for your Dad's care. Since your Dad has Alzheimer's, he is going to need all of the money he has to pay for his care. Your brother is NOT entitled to ANYTHING!

Is your Dad living with you or is he in Memory Care Unit or Assisted Living facility?

Your brother hasn't seen your Dad in 25 years and now your brother wants your Dad's stuff?

Tell him to kiss your *donkey* and don't call anymore.

He's not entitled to one penny.

Yep, I totally agree with Shaking......Ugh, the nerve of some people. I just wonder where this sense of entitlement comes from. Give him nothing.