Caliber is the size of the barrel's inside diameter, in fractions of an inch. A .25 caliber pistol fires a bullet that is about 0.25 inches across. Pistol can range from very small (about 10 caliber) up to very large (75 caliber) and there are hundreds of different cartridge sizes in between.
You will have to define what "large caliber" means to you and weather the pistol is a revolver, singleshot, blackpowder, rifmfire, centerfire, pinfire, semi-automatic.
most any large gun store will have them.
A large revolver
No. They will be too large to fit in the gun or be fired out of the barrel.
Small Pistol Primers are used for small caliber pistols, any of the various 9mm calibers such as the .380, the 9mm luger, the 9x18 makarov, the .38 special, the .32 acp, the .25acp etc. and even some larger calibers such as the .40 S&W. Large caliber pistol primers are used in .45 caliber and larger. Still other calibers, such as the .357 Magnum for instance, require primers known as magnum primers.
No. the AK-47 assault rifle is chambered for the 7.62x39mm round, which is equal to the .30 caliber. The .45 caliber is simply too large for the AK-47's bore, not to mention it is a pistol cartridge, which has a completely different design than a rifle cartridge.
No. Paintball barrels are .68 caliber and have relatively huge threads compared to airsoft guns. Not only would they not fit, they would not work due to the large space between the barrel and the airsoft pellet.
The maker of your revolver was Iver Johnson Arms and Cycle Works.This 5 or 7 shot revolver was called the Birds Head grip model,and was made from 1873-1888.IT was chambered in .22cal(small frame)32cal(medium frame)and 38,or 41cal(large frame).Yours will have either a 2 1/2in barrel(small frame) or 2 7/16in barrel(large frame).I must include that barrel length,s of 10in.have been encountered with this model.
It's difficult to answer what is "average." Pistol bullets can be as small as .17 caliber (although not common) and as large as .950 caliber (also very uncommon). The most common semi-auto handgun calibers are .22, 9mm, .40 (depending on where you are) and .45. The most common revolver calibers are .22, 38, 357, and .44, but there are a lot of other calibers available.
.22-.50
The medalist is a .22 caliber pellet pistol. You need to purchase .22 cal pellets not .177 cal pellets. you can find them at most large sporting goods stores.