Why are there so many gun models using the same calibre? Doesn’t the bullet determine most of the lethality and range, while the gun is just the vehicle that fires it?

Question

Why are there so many gun models using the same calibre? Doesn’t the bullet determine most of the lethality and range, while the gun is just the vehicle that fires it?

In: Physics

Answer 1

Caliber is only a measure of bullet diameter, and there are a lot of other factors to consider when deciding what gun is right for the job. .30 Carbine and .30-06, for example, are the same caliber (more or less) but wildly different cartridges.

Even guns in the same cartridge may have many different uses. An AR pattern rifle in 5.56mm/.223 with a 12″ barrel is a nice thing to have if you’re fighting from an armored vehicle, but isn’t a good choice for taking White Tail deer.