Caliber is a measurement of the diameter of the projectile or case of a cartridge for a firearm. 1.00 caliber is equal to one inch, .50 caliber is equal to one half inch. Firearms are made to a wide variety of calibers, from .17 through .50 mostly. The weight or length of the 'bullet' or projectile can vary a lot even in a particular caliber. The velocity of a bullet as it leaves the gun multiplied by its weight equals the force it can exert on a target. There are also some bullet diameters that are typically expressed in millimeters - like 9 millimeter. The way calibers and cartridges are 'named' can be complex depending on where it was originally made or when it was first made. Cartridges that have been made for 70-120 years are sometimes named by the caliber and the year it was invented, the caliber and the company that originally created it, sometimes for the particular gun it was made for and the caliber. There are many sites online that present long lists of ammunition types.
They are two different calibers.
The size of the projectile.
The size of the projectile.
Both can refer to 45ACP. 45 alone can also refer to 45 Colt
Length, dimensions, and possibly caliber. The 600 was made in calibers the 400 was not.
10 has short action, 110 has long action. Differerence is about 1 /4 inch in the length of the Receivers. Short action calibers include .223 up to .308, Long action calibers include 270, 30-06 and magnum calibers 7MM and up to 458 Magnum.
No
The model 100 is a .177 caliber air rifle. The model 101 is a .22 Caliber rifle. Basically the same air rifle just different calibers.
Dozens of calibers from .22 up through major hunting calibers.
No published data to give a definitive answer.
Weight and construction
Different calibers. The Model 19 is in caliber 9x19mm, the Model 23 is a .40 caliber. The 19 holds more ammo in the standard magazine. External dimensions and weight are the same.