This posting will deal with handguns, specifically revolvers.
First, let's discuss some common terms.
Revolver: a weapon, usually a handgun, in which the ammunition (cartridge) is loaded into a cylinder. The cylinder revolves aligning the cartridge with the chamber and the firing pin.
Single Action: A type of handgun in which the shooter must manually pull back or cock the hammer to place another cartridge in the firing position. Single Action handguns can usually be identified by one of two loading mechanisms. On many there is a gate on the right side of the cylinder through which cartridges are loaded and spent casings ejected.
Double Action: A handgun in which the hammer is cocked and the cylinder rotates with each pull of the trigger. Double Action revolvers can usually be identified by the fact that the entire cylinder rolls out so the handgun can be easily loaded.
Break Action: A pistol in which the barrel and cylinder are released as a unit to allow loading.
Bullet: Projectile portion of a cartridge.
Shell: A shotgun cartridge.
Chamber: The portion of the barrel into which an unfired cartridge (round) is either aligned (revolvers) or inserted (pistols).
There are a couple of characteristics of revolvers that movies and television seem to routinely ignore and it drives me crazy! Silencers DO NOT work on revolvers--there are too many openings through which sound can escape! Another pet peeve of mine is the absolute misconception that six-shooters have more than six cartridges in them. We all remember the B westerns and crime movies we saw as kids where the hero and the villain seem to shoot forever without having to reload. If you have a gunfight in your story count the times your characters discharge their weapons and ensure that the rounds fired do not exceed the capacity of the weapon.
For a detailed description of various types of weapons consult the ATF Guidebook - Importation & Verification of Firearms.
Ammunition, and Implements of War
In the next post I'll talk about revolvers in more detail.