These guns are loaded by first clearing the bore of oil and other substances, then loading a measured powder charge, followed by the projectile(s). In the case of a shotgun, multiple projectiles will be used.
Older styles look like the old rifles you may have seen in the movies, with the hammer off to one side of the rear end of the barrel, usuallly the right. This is known as a sidelock design.
In recent years the trend has been towards "in-line" designs, which place the components of the gun and load all in a row, i.e. in-line with one another. Generally these designs offer better reliability and may fend off foul weather more efficiently than sidelock guns.
All varieties of these guns can be extremely accurate (despite campfire talk to the contrary), but they suffer the disadvantage of being quite slow to load, so you generally only get one shot at the game you're pursuing.
