It might be better to call them arms, as in SAAMI (Sporting Arms, etc.), and that's the closest word that means the same thing as weapon. But I guess they could be a tool, too.
Remember the old B-westerns (if you're old enough) when the sheriff was nailing the wanted poster to a tree by pounding it with the butt of his revolver. Those were real Colt revolvers, too.
Mustard and custard!
It's still a firearm even when unloaded and it's not empty if there are still cartridges in the magazine--whether or not the chamber is loaded. If you don't think so, well, tell it to the judge.
But things do change. There is a fairly well known German purveyor of arms and outdoor goods, rather like Cabellas, Franconia, used to be called Waffen Franconia, or I think they were. Wonder if they thought the word Waffen (arms) was bad or, more likely, too narrow.
Shoot low, sheriff. They're riding Shetlands!
Underneath the starry flag, civilize 'em with a Krag,
and return us to our own beloved homes!
Buy War Bonds.