If you starting looking carefully at military bolt action rifles, you will find that they generally all fall into one of three categories:

Rifles: 30-32 inches / 760-810mm
Short Rifles: 24-26 inches / 610-660mm
Carbines: 17-20 inches / 430-510mm

How did these different standard lengths come about, and why are the Italians and the Russians different? Let's have a look...