The simple outward appearance of the modern shotshell conceals several
important elements which play a critical role in making this form of
ammunition fire. The case, crimp, powder, primer, shot and wad all
come together to ensure your shotshells fire safely and accurately
every time. Click on each term or to learn more about their importance
and function in today’s modern shotshell construction.
Case (a.k.a. The Hull) – The modern shotshell case is
similar to the case on a rifle or pistol cartridge. The hull
is normally made from plastic, paper or, in rare cases,
brass. It will also have a steel or brass head and rim
attached. The case is designed to contain the powder charge,
primer, wad and shot. Hulls are available in a variety of
lengths such as 2.75”, 3”, 3.5”. The length of the hull
refers to the overall length when the shotshell is fired.
Powder –The term for any chemical compound that is
used to propel the shot and wad out of the barrel when
ignited by a struck primer. Powder is commonly found in two
varieties, smokeless and black. Smokeless powder found in
modern ammunition has a significantly reduced smoke
signature. Black powder, on the other hand, is very smoky
and can be corrosive.
Shot – The shot is the collection of small pellets
that act as the projectile in a shotshell. They are commonly
made of lead, steel or bismuth. The size of shot varies
depending on application.
Primer – The primer is the small circle on the base
of the shotshell. The Primer is made up of the anvil, primer
cap and priming compound. When the primer is struck by the
firing pin it ignites the powder contained inside the case.
Crimp – This is how the shot is retained in the case.
There are two main types of crimps: roll and folded. The
folded type of crimp is the most common on shotshells. Some
roll type crimps will decrease capacity of your shotgun due
to the extended length of the crimp.
Wad – The wad is a disk or cup that is used to
separate the powder from the shot. It also seals the
propellant gases behind the shot column to provide the best
level of velocity.