Generally, later guns had longer barrels and therefore higher muzzle velocities of the projectiles. The ratio of the projectile diameter to barrel length in naval guns is referred to as gun caliber. The table below shows the improvements to be gained by increasing gun caliber. Shell Weight 2,700 lb. The second factor that affects overall firepower is the rate of fire.
Smaller guns are easier to load, and therefore can fire more rapidly.
Other factors affect rate of fire, such as the design of the shell handling rigs and loading mechanisms. And the skill level of the crew contributes greatly to the rate of fire of any gun as well. A common way to increase the rate of fire of a battleship is to increase the number of barrels in the main battery. To a lesser degree, the arrangement of those barrels in turrets also plays a factor. Obviously, having twelve guns is better than eight since more shells result in greater hit probability.