A shotgun cartridge is designed to be fired from a shotgun. Most shotgun cartridges are designed to be fired from a smooth bore barrel.
The cartridge has 5 main components:
- An outer case comprising of a plastic hull with brass base section
- A Shotgun primer
- The Propellant charge
- Shot wad unit
- Shot
The image on the right shows a cartridge with 4 of the component parts visible. The primer is not visible from this angle as it is located in the center of the brass base.
The shot wad can be bio-degradable fibre, as in this cartridge, or plastic depending on the manufacturer specifications.
Traditionally shot is made from lead composite. Currently there are a number of alternative materials that shot can be made out of including steel, bismuth or tungsten composites. These new materials are generically referred to as lead free shot. If a shooter wishes to use lead free cartridges, they must check that their shotgun, barrels and chokes are proofed and capable of firing non-lead cartridges. Steel is the main concern and all new barrels and chokes will state if steel shot cartridges can be used in them.
The cartridge is generally sealed by rolling and crimping the end of the plastic hull as can be seen in the picture.
The firing cycle of the cartridge.
- The primer is struck by the firing pin.
- The primer ignites the propellant charge which burns vigorously releasing a vast quantity of hot gas creating pressure.
- This production of gas generates extreme pressure which forces the wad against the shot.
- The Shot, in turn, forces open the crimp at the end of the cartridge body.
- The wad and shot, which are still under extreme gas pressure, continue to travel out of the cartridge, down the barrel, out the muzzle and towards the target.
This whole process happens very quickly. The time from the trigger being squeezed to the shot and wad exiting the barrels is a fraction of a second.
