A firearm is a weapon [period]. It can be used for all kinds of things but if it uses gunpowder and fires a projectile, its a weapon. If it is never used for anything other than a lamp stand it is still a weapon none the less. Sport shooting is the demonstration of personal prowess with a [weapon]. I am not inclined to believe that people who are ok using rifles, handguns, bow/arrow, swords, flails, foils, polearms or any other weapon are completely devoid of the concept that these are weapons. At some point if for no other reason than safety, knowledge and respect of history- a person would have to qualify that in their mind.
So a baseball bat is a weapon? And a car? And a truck? And a pencil? I mean, all these things are dangerous when used in a dangerous way thus making them weapons all the time by your definition. Nearly anything can be a weapon. Not all things are at all times.