Removing a shotgun shell from an extractor chamber
Shotgun Mechanics

Shotgun Ejectors and Extractor

Learn about the history and mechanics of the shotgun extractor and ejector.

I recently received a text from a buddy with a number of photos of a minty 20ga Fox Sterlingworth shotgun that had come up for sale. The gun was a Utica, NY gun, so not a Philly Fox, but a Fox no less. The thing that made me look twice at it was an inlay on the forend. It was clear that there was no external button for the forend latch and it was the more simple ‘press on’ style where the forend cams onto the forend latch. It did not occur to me at first but after additional inspection of the gun, it was clear that the additional forend metal was related to this being an ejector gun. This being a field grade gun, the addition of ejectors made it a more rare and unique gun than the standard extractor version of a Sterlingworth.

Guns (autos, pumps, and doubles) are all made to function more than once. This seems very rudimentary, but in truth, being able to contain a small explosion and propel a shot charge or solid round down range is no small feat of engineering. When we place a cartridge, shell or round into a gun, that round is typically guided into the chamber end of the barrel where it is then held in place by a piece of metal that mechanically locks in place. The trigger is pulled, the round is fired and once the fireworks are over, we are left with a chamber that needs to be opened, ie. unlocked and a spent shell or casing to remove. This process is typically done via mechanical advantage. 

A Fox Sterlingworth with Extractors

The Science of a Shotgun Chamber

Mechanical advantage is needed to remove spent casings because all cases, plastic or brass, expand inside the chamber when the gun is fired. The pressure developed when firing the gun is more than sufficient to expand any casing material and in fact, most casing materials are somewhat pliable for this exact reason. The force of the gunshot is not actually contained by the casing material, but rather the walls of the barrel and locking mechanism that create the ignition chamber. As a result, the casings expand as much as the chamber allows and in extreme cases can imprint on a rough chamber. Rifle shooters can inspect brass casings to determine how smooth a chamber has been cut in their barrel because marks will be transferred to the brass casings and very visible.

Long story short, the expansion of the case in a chamber increases the coefficient of friction between the spent round and the chamber that contains it. That fact plus the necessity of locking the rear of the barrel closed (as described above) typically means there isn’t much to ‘grab onto’ once that shell has been fired. Enter the extractor. 

The Invention of the Extractor

Extractors were invented to provide the shooter an easy way to remove spent casings from the chamber of a gun. This problem did not exist for the earliest shooters, those before the development of the self-contained casing. Initially of course we simply put powder, shot and wad down a barrel, no case needed. With the development of the casing, came the requirement of removing the casing from the chamber and so began the development of the extractor alongside of the metallic cartridge. 

Most common firearm rounds, shotgun or rifle, are either rimmed or rimless. Other varieties include semi-rimmed, rebated rim or belted magnum though all variants of the cartridge rim serve as a surface upon which the extractor acts (and sometimes for headspacing a firearm). In the case of the modern shotgun extractor, the interaction happens between the rimmed brass (or steel) base of the cartridge and the extraction device on the gun.

Pump shotguns and autoloaders typically have an extractor claw that is an integral part of the shotgun bolt. The bolt is the piece of metal that moves forward and blocks the rear of the barrel, locking in place to form the ignition chamber. Once the gun is fired, the bolt moves back via pressure from the charge (autoloaders) or by actuation of the pump (pump shotguns). The extractor claw hooks over the edge of the shell and begins to physically pull the shell out of the action. Typically there is a kicker that is also actuated by motion of the bolt that strikes the brass of the shell in some way to eject it from the chamber of these inline firearms before the next round is fed into the action from the magazine. 

For double guns, the actuation is a bit different. There is no bolt that moves in these guns and the breech face is the piece of metal that caps off the rear of the barrels. This face is carefully fitted such that when the gun rotates on the hinge pin, the breech face locks against the barrels. The lockup is provided by hooks on the barrels and catch devices in the action of the gun that are typically actuated by a top lever (side lever, under lever, or another device).

When placing shells into the barrels of a SxS or O/U an inspection of the chamber will reveal a ledge where the rim of the shotgun shell rests when the action is closed. There is usually a portion of that rim that is cut away allowing a piece of metal to be fitted. This piece of metal slides on a rod that is oriented forward into the barrels. In the case of an extractor, this may be a single piece of metal. When the gun is closed this piece of metal is fitted perfectly such that it matches exactly the ends of the barrels and as a result the breech face of the action. 

This piece of metal is actuated by a cam motion when the gun is opened. Typically this cam system is an integral part of the forend where a piece of metal pushes on the rod which then lifts the shells from the barrels when the gun is opened. This happens every time the gun is opened, whether the shells have been fired or not. Though there are variants on this design, it is one of the simplest methods for shells to be extracted from the barrels. 

Then Came the Ejector

Shotgun shells ejected from a shotgun

Ejector mechanisms in shotguns include the basic elements of extractors but add in spring-loaded elements to forcibly eject the spent cartridges clear of the chamber. In general, ejector devices contain either a flat spring or coil spring that is compressed and locked when the gun is opened and closed during loading and unloading. 

The easiest way to look at a firearm and determine if it is an extractor or ejector is to look for a single extractor piece versus a split or two-piece extractor. Ejector guns have two pieces, one for each barrel where extractor only guns have a solid piece of metal.

Ejector guns are unique in that if only one shell is fired, upon opening the gun, only that ejector will fire. This is a result of the interaction between the fired (uncocked hammer in the action) versus the unfired (still cocked hammer in the action). When a barrel has been fired the action of re-cocking that barrel’s hammer also triggers the ejector. The unfired barrel is not experiencing the action of cocking so there is no triggering of the ejector associated with that barrel. If this were not the case, both ejectors would fire each time one hammer was uncocked and eject live rounds from the barrels (not good). 

All of that is to say that the little 20-gauge Sterlingworth in question had additional parts in the forend that contained the spring mechanism that was part of the ejectors. The visible metal in the forend was part of the ejector system and required to add the strength needed to be contained inside that small forend. And as such it is a gun where you can determine if it is an ejector or extractor simply by looking at the forend.

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