Technical Diagrams
Below are diagrams illustrating some of the terms described in the 'Terminology' section.
Primer types:
Muzzle-loading rifles and actions:
Clay pigeon shooting layouts:
Cartridge case rims

Headspace
Diagram showing headspace and various rimmed cartridges

Primer types:
Berdan primer

Boxer primer

Note the different position of the anvil and flash holes. Berdan primed cartridges are not easily reloadable, whereas Boxer primed cartridges are.
Rimfire primed cartridge

The priming composition is an integral part of the cartridge and as such it is not practical to reload.
Rifle cartridge

Shotgun cartridge

Muzzle-loading rifles and actions:
Flintlock action

Matchlock action

Wheel-lock action

Percussion lock action

Martini action

Mauser '98 action

This is an example of a forward-locking rifle. In a forward-locking rifle the locking lugs are at the front end of the bolt, locking into recesses in the action. There is additionally a third lug at the rear of the bolt.
Clay pigeon shooting layouts:
Skeet

The two towers are 40 yards apart. Points 1 - 7 represent the shooting stations.
Down-the-Line (DTL)

Points 1 - 5 represent the positions that the shooter stands at, 3 yards apart. The trap is 16 yards from the shooter.