Your car is very effective at killing. It weighs several tons and goes up to a hundred miles per hour. It is obviously built for nothing other than killing.
Cars are even the number one cause of accidental death. Much higher than any other weapon.
A car's purpose when it is built is not to kill people. In fact, lately cars have been built to try and protect the driver and other drivers in case of an accident. Guns on the other hand, are, and over the years people have built them to be even better at it.
Because this was meant to kill
That is an extremely high end Anschuetz .22lr target rifle. It was built for one purpose, not to kill, but to make very tiny groups on paper. I wouldn't consider that a weapon.
I don't believe any item is automatically a weapon. How it's used makes all the difference. A pencil isn't a weapon. However, in the right hands it can become an effective weapon. In court when they bring out the evidence, the weapon used would be a pencil. Now is a pencil a weapon? Now don't get me wrong, a gun can be used as a weapon. All too often they are. The majority of firearms in the U.S. aren't used to kill or wound anyone, therefore the U.S. has few weapons that are guns.