Most are in .380 ACP caliber. Sometimes called 9mm Short in Europe (or 9mm Corto or 9mm Kurz) What is marked on yours?
Caliber is the size designation for rifle and handgun bullets. Guage is the size designation for shotgun rounds.
30-06 caliber bullets
Depends on the caliber.
.32 caliber
The model 19 is a 9mm only proposition. The model 19 is not available in .40 caliber, but the model 23 is the same size gun and it is a .40 caliber gun. Some people would say that the model 23 is the .40 caliber version of the model 19.
With VERY FEW exceptions all BB guns use the same size BB .177 Caliber.
If you state the caliber we could then determine the size of the action.
On the barrel of most guns produced, the proper caliber/gauge is stamped as well as size/ type. That being said I think the model 16 was a semi-auto .22 caliber, firing a .22 caliber long rifle round.
they are exactly the same
Assuming you are talking about shooting a patched round ball, then .490 would be the most normal ball size for a 50 caliber. Of course other types of projectile might be used, such as maxi-balls or bullets with sabots, depending upon the type of gun and the purpose of shooting.
American Heavy Machine Guns in WW2 fired .30 caliber rounds. The .50 caliber machine gun was 0.50 caliber which is 1/2-inch diameter and about 2 inches long. The shell before firing is about 6 inches in length.
The standard caliber is .45 acp. That is a short fat pistol caliber that fires a 230 grain bullet at about 800 feet per second velocity. Lighter bullets down to about 185 grains are available, and they travel faster, possibly as high as 1100 f.p.s. The model 1911 pistol is a semi-automatic, not to be confused with an equally famous revolver made by Colt, often chambered in what is also called .45 caliber, but that model 1873 revolver would use the .45 Colt or .45 Long Colt cartridge, which is a rimmed revolver round, much longer in size that the .45 acp, and firing a heaver bullet at similar velocity.