Always treat guns as if they are loaded. Even if the slide it locked back or the bolt is removed. The reason for this is very simple.
Empty guns kill people. This was my Dad’s mantra for gun handling when I was a kid.
We have all seen the news report of an accidental shooting because someone thought the gun was empty. They all say the same thing. If I thought it was loaded I would not have pointed it at my friend, sibling, parent, etc.
If you follow this rule you will greatly reduce the likelihood of someone accidentally getting shot.
My Dad taught me this as a child. He would freak out and knock a gun out of your hands and slap you if you pointed a gun in his direction. It was a bit harsh, but my brother and I learned very quickly to always be aware or where the barrel is pointed.
You will notice that people will handle a gun very differently, to the point of complete indifference as to where it is pointed, when they believe it is unloaded. This is not a good practice.