Shotguns: Actions and Designs

The early history of true shotguns begins in the 1800s, when people began to use them to hunt birds. During that time, the flintlock firing mechanism was the ignition system of choice and hence, it should be no surprise to know that early shotguns used them. The problem with such mechanisms is that there is a noticeable delay between pulling the trigger and the weapon actually discharging. The Rev. Alexander Forsythe, a Scottish clergyman and an avid hunter, noticed that the local birds would see the flame in the pan and immediately change direction and thereby escape. Hence, he set about inventing the percussion lock, which was the next big development in firearms technology and was also used by other firearms besides shotguns. The percussion lock was eventually replaced by modern cartridges, which we use to this day.

Shotguns come in both single barrel and double-barrel types. Double-barreled shotguns have two triggers, one to discharge each barrel. Of the double barreled shotguns, there are two types: "side by side" type and "over and under" type. What this means is how the two barrels are positioned. In "side by side" types, the barrels are placed beside one another, whereas "over and under" types have one barrel positioned on top of another.

"Side by Side" type shotgun

"Over and Under" type shotgun

Double barrel shotgun barrels are never attached parallel to each other, but instead set so that their shot will converge at some point (usually at 40 yards distance). In some shotguns, one of the two barrels may be made different from the other. For instance, one may have rifling and the other is smoothbore, or one barrel may be choked for closer shooting. In other cases, both barrels may be made as identical as possible.

Of all the actions, the break-open action, such as the two images above, is the most common type and has been around for a long time. This is a breech-loading mechanism. It was realized in 1875 that the movement of opening the action could also be used to cock the weapon at the same time. The first such cocking mechanism was pioneered by Anson and Deerley for their hammerless shotgun and it is still used almost unchanged to this day. Break-open actions are the most common type used for shotguns.

Another action that was invented in the mid 1800s and rare today, is the side-motion action. In this type of action, the barrels are mounted on the edge of a metal disc. A lever in the bottom of the stock rotates this disc, which causes the barrels to move in an eccentric motion, where they can be reloaded.

Another action that was invented in the 1800s, but is rare now, is the sliding barrel action shotgun. There are only a few manufacturers around that make this type currently and it was never as popular in the 1800s either.

Sliding Barrel Action Shotgun

Lever action shotguns were popular in the 1880s. The Winchester model M1887 was designed by John Browning and became a best-seller for the company. This was the first truly successful model of a repeating shotgun. This action allowed for users to load multiple cartridges into the weapon, not just one or two cartridges. Their popularity waned after the design that we're about to study in the next paragraph was introduced, and we don't see too many lever action shotguns these days.

Lever-action

The action that replaced the lever action design is the pump action shotgun design. The first popular ones of this type were the Winchester M1893 and M1897 models, which were designed by John Browning! It must be noted that when Winchester originally asked Browning to design a repeating shotgun in the 1880s, he had argued that a pump-action mechanism shotgun would be the most appropriate design, but Winchester was a lever-action manufacturing company, so they persuaded him to design a lever-action shotgun, which was the M1887 model described above. However, they did later manufacture his pump-action design as the Winchester model M1893, which was later improved to the model M1897. It must be noted that the M1897 shotgun gained so much popularity that it was used by US soldiers in World War I, where it was found very useful for trench fighting. Its quick shooting speed and massive stopping power made it a very effective weapon for US soldiers to have. In fact, the German troops feared this weapon greatly and the German High Command even attempted to have it outlawed in combat, by citing Geneva convention laws (this coming from the same people that allowed the use of poison gas!). The pump-action shotgun design is still popular to this day.

Pump Action shotgun

There are also semi-automatic shotguns, where some of the force generated by the firing cartridge is used to eject the old cartridge, cock the action and load a new cartridge. Semi-automatic shotguns use a variety of mechanisms: long recoil action, inertia operated action or gas-operated action. The first successful semi-automatic shotgun was the Auto-5 (or A-5) action first designed in 1898 by (surprise, surprise) John Browning! The Auto-5 model remained in production until 1998!

Semi-automatic Remington Model 11 shotgun using long-recoil action

Bolt-action shotguns also exist in the wild, though they are not common. One particular model was manufactured in .410 caliber by the Ishapore arsenal of India, based on the Lee-Enfield SMLE Mark III model.

Ishapore .410 caliber bolt action shotgun. Click on image to enlarge.

In the next post, we will look into more about shotguns.

Actions: Break Open Action

When we last left off on our study of firearm mechanisms, we were still dealing with muzzle-loaders and the percussion cap. While we did study some details about breech-loaders, we really didn't study any of the mechanisms associated with them, aside from the Ferguson rifle. The rise of breechloaders started with the rise of metallic cartridges. In this post, we will study a common breech loader mechanism called the break-action. This is also called top-break or break-barrel action Actually, we did study a bit about break-actions in our discussion about revolver loading mechanisms earlier.

In a break action weapon, the barrels are hinged and break open on top to expose the chamber. One of the well-known examples is a Lefaucheux gun from 1836, which used pinfire cartridges.

There is a lump under the barrels through which a pin passes and the barrels pivot on this pin. There is also a slot cut into the other side of the lump. When the barrels are closed back in place, the user turns the lever in front of the trigger guard, which pushes a projection into the slot, thereby keeping the barrels from moving upwards.

When the barrels are tilted upwards, the user can remove the old cartridges, insert the new cartridges into the barrels and then close and lock the mechanism.

Of course, this mechanism was not always the strongest, but people began to improve upon this basic idea.

In the picture above, we have a W.W. Greener gun using his Treble Wedge-fast mechanism invented in 1865. This gun has three ways to hold the barrel in place. Under the barrels, notice the two projections with slots cut through them. A holding bolt through each one of these slots holds the barrels and prevents them from pivoting, when locked. In addition, notice the top of the barrel also has a projection with a hole through it. When the barrel is locked into place, a cross bolt is pushed through this hole to hold it in place. Each of these holding bolts by itself is capable of holding down the barrels, but the combination of all three together makes the action a strong one indeed.

In the picture above, we have a Greener Improved Treble Wedge-fast mechanism from the top view. When the user pushes the barrels back in place, they can use the long lever and lock all the bolts before firing the weapon.

Of course, it was soon realized that the movement of opening the barrels could also be used to cock the weapon at the same time and this was taken advantage of. Anson and Deeley made the first successful mechanism of this type in 1875, which was followed by other manufacturers such as Westley Richards, Greener, Purdey etc.

The mechanism above is an example of a Greener "Facile Princeps" mechanism. When the barrels are opened, the small lump C pushes one end of hammer A. Since the hammer turns about a pivot, opening the barrel turns the hammer A further back. As the hammer is pushed back, it also compresses the v-shaped spring B. The barrel is opened until the hammer cocks. This happens when A rotates sufficiently for the tip of lever D to hold A as shown in the image above. The weapon can now be loaded with cartridges and closed.

When the trigger is pulled, lever D is pivoted and thereby releases the hammer A. The spring pressure from the v-shaped spring B makes it open and thereby rotates A, which makes the beak of A sharply strike the center of the cartridge and fire it.

It was also realized that the action of the falling barrels could also be used to eject the old cartridges automatically as well. The first example employing this idea was the Needham gun of 1874, but variants of the basic principle were made by several others including Perkes, Anson and Deeley, Baker, Trulock, Ross, Holland & Holland etc.

In the above two images, the extractor lever is clearly visible. When the gun is closed, the extractor sits flush with the barrel. When the gun is opened, the extractor lever pokes out of the barrel and catches the rim of the cartridge and pushes it out of the barrel.

Thus, the user can eject the old cartridges and cock the gun at the same time, merely by the act of breaking open the weapon.

This action is a very compact and straightforward mechanism, which makes the cost of manufacturing pretty low. Since the extractor is part of the barrel, this makes it very suitable for guns that have interchangeable barrels.