Shotgun Cartridge Components Explained

Shotgun cartridges have similar components to that of a rifle cartridge.  The components of a shotgun cartridge are:

The Projectile

The Case

The Wad

Propellant 

The Head

The Rim

The Primer

Primer                                                                                                                                                   

The explosive center of the shell.

Firing pin hits primer.

Powder in primer ignites.

Ignites the propellant in the shell.

Propellant

Fast burning material that creates a gas expansion in the shell.

This propels the shot down and out the barrel.

Case

The Shell Case is what houses everything.

The common sizes of Shotgun Shells are

10 Ga

12 Ga

20 Ga

.410

What does the “gauge” of a shotgun shell mean?

Gauge originated when cannons and muzzleloaders were common.

The spherical lead ball was a fraction of a pound.

A 10 Gauge ball was 1/10 of a pound.

A 12 Gauge ball was 1/12 of a pound.

The bore was a 10, 12 or 20 Gauge bore… this carried over to the modern shotgun.

A smaller number meant a bigger ball, which meant a bigger bore.

What size is a .410 shotgun.

.410 is designated for a caliber number.

It is slightly larger than a 40 caliber cartridge.

The bore is about 10 mm.

Uncommon shotgun shell sizes

4,8,16,24,28,32

These are either not common or considered obsolete.

The 10 gauge is becoming less common as well due to Lengthening and strengthing of 12 Ga shells.

Common Shell Lengths for Shotguns

2 ¾, 3, 3 ½ inch

Shotguns will have the length etched on them.

You may go shorter than the shotgun length, but not longer.

The Head

The head is the brass around the base of the cartridge.

The Rim

The rim is the small brass ring on the bottom of the shell.

Allows ejection of the shell by the action of the shotgun.

Keeps the shell chambered correctly.

The Wad Column

Made up of 3 components

The Gas Seal

The Cushion

The Shot Cup

Some wads are designed to be all three in one.

The Gas Seal

This is designed to keep the expanding gas from moving behind it.

This keeps all expansion and momentum going forward.

The Cushion

This is the shock absorber

It prevents sudden violent expansion of gas from warping the shot (soft lead)

Shells have different propellant and shot quantities.

The cushion also takes up the empty space so the shell is standard length.

The Shot Cup

The cup houses the shot and keeps it together as it travels down the barrel.

It is slotted, so once it leaves the barrel, it tears away from the shot.

This allows the shot to travel freely in air.

The Projectile

There are two basic projectile types.

Shot, or pellets

Slugs

TPP 128: Shotgun Cartridges and Shells from Ken Jensen

Shotgun Slugs

Shotguns were designed to shoot the ball type shot from the old muskets.  These are called “Pumpkin Ball” slugs.

Since then, slugs have gotten much more sophisticated with design.

Some of the benefits of slugs today:

These new designs allow us to bring some “rifle” qualities to shotguns.

All the force is focused to one spot.

This allows for greater impact or penetration on large...