Written by Neil Harmse

Chapter 21. Shotgun Cartridges and Their Development Over the Years

Today most wing and clay target-shooters using modern shot cartridges show very little interest in the ammunition they use, apart from what they feel is their favourite brand and the ideal load for their specific sport.

To gain a better understanding of the development of centre-fire ammunition, we need to go back in time to the year 1850 and onwards, after the first breech-loading centre-fire guns became available.

Prior to then, from 1815-1835, gunsmiths were competing to get away from the flintlock. In 1830 the percussion cap, which was the intermediate stage on muzzle loaders, led to the development of pin-fire guns and subsequently opened the way for breech-loading centre-fire cartridges and guns. Thanks must go to Mr JV Needham, who invented and produced the ‘hammerless’ or internal hammer action that started the revolution in the development of the ‘modern’ style of ammunition. The centre-fire cartridge was designed.

In 1875, William Anson and John Deeley – who were both employed and associated with Westley Richards – developed and introduced the Anson and Deeley box-lock action, which was so successful in design that it has seen very little improvement up to the present day. This action was ideally adapted for the modern centre-fire cartridge. The action was less expensive and easier to produce than the traditional side-lock action, which was carried over from the days of the hammer and percussion actions. The Anson and Deeley action helped place guns in the hands of general shooters who were neither nobility nor landed gentry and could not afford expensive, handmade side-lock guns from top-name gunsmiths, but also wanted to get involved in the sport of ‘shooting flying’.

Side-locks were, and remain, more complicated to produce and are today sought after mostly for more expensive handmade top-grade guns.

The first breech-loading centre-fire ammunition was carried over from the days of muzzle loaders and used the traditional black powder propellant. When fired, these cartridges produced clouds of white smoke which sometimes obscured visibility for follow-up shots or even seeing the hits on targets. It was not unusual to see a shooter smartly dodge to one side to get past the cloud of white smoke in order to see the hit on his target. Soon there were calls for cleaner-burning propellant, which led to the development of Schultz powder. This burnt a lot more cleanly, producing less smoke and recoil, and was not as noisy as the old black powder loads. It became popular for its advantages to shooters. Further developments in modern smokeless Nitro powders led to more efficient and faster ignition, with more regular ballistics, less pressure and the absence of fouling, which also meant less corrosion in gun barrels.

Today cartridge manufacturers are continually striving to develop and improve the quality of their cartridges, with a view to more environmentally friendly components and consistent results. This is true of all the components which make up the modern cartridge.

The first step in the ignition process is the primer. Percussion ignition was first invented in 1807 by Rev Alexander Forsyth, a Scottish clergyman, but required a lot of refining. The early primers were very corrosive and could be unstable. Modern primers have vastly improved and have standardised on a 209-boxer type for shotguns which are largely non-corrosive, give quick and reliable ignition, and are well sealed and protected from contamination by moisture and oils, which are the cause of many misfires.

The following is a basic explanation of the firing procedure and sequence:

When struck by the firing pin of the gun, the primer should ignite, causing the propellant powder to burn and form a gas. This creates pressure, driving the wad and shot load up the barrel and, on exiting, causes the shot to spread into a pattern given by the choke selection, then on to the target.

Briefly, the modern shotgun cartridge consists of a brass or metal base, rimmed to fit onto the extractor or ejector rim of the action and chamber of the gun. The primer fits into this brass base. The body or case of the cartridge, which was traditionally made of varnished paper or card, is today usually plastic. The length of the cartridge body depends on the requirements of the gun chamber. This can range from 2½” (65mm) to 2,6” (67mm), 2¾” (70mm) and 3” (76mm). These are nominal lengths of factory cartridges, but exceptions are a shorter 2” (50mm) and a magnum 3½” (89mm), which are sometimes called for. The 67mm case was designed to allow the use of this cartridge length in either 65mm or 70mm chambers, allowing a slightly heavier load than normal for 65mm chambers.

Cut-away cartridge and wads.

Early cartridges all had fibre or compressed paper or card wads. Today the wad can consist of either formed or moulded plastic or biodegradable fibre. The plastic wad normally has a cup-shaped fore section with segmented ‘petals’ which hold the pellets in place and peel back and open as the shot column leaves the muzzle, releasing the shot in its forward motion to start spreading. This allows for a more controlled spread and pattern.

The fibre wad remains behind the shot load, acting as a gas seal and pushes it forward, with the shot column spreading faster on exiting the muzzle to create a more open pattern. The fibre wad is mainly used on game loads.

Most modern cartridges are enclosed with a segmented ‘star’ crimp at the mouth. Some cartridges can still be found with a ‘rolled’ crimp, but these are normally older or traditional loads.

As previously mentioned, with the trend towards environmental awareness, cartridge manufacturers have made great strides in the development and use of components that are ‘greener’ than in the past.

As a result of concerns about pollution of the environment (especially wetlands) caused by lead from shot pellets, cartridge manufacturers are now producing non-toxic shot using Bismuth, copper-coated or annealed steel pellets. These have a number of drawbacks, but research is ongoing. There is also a marked controversy in the claim that pollution from lead pellets causes problems. To date, no proof of this has been forthcoming, but it

is nevertheless wise to be proactive in this regard. For many years, lead shot had a 0,5% antimony added for hardness and this is now also treated by electroplating with either copper for hunting loads or nickel for clay target, small birds and pigeons. This reduces pellet deformation, keeping the pellets spherical to allow consistent patterns.

Pollution from wads has also been problematic, mainly in areas where high-volume shooting takes place. A number of game loads are now loaded with biodegradable fibre wads, which have a short lifespan once exposed to outdoor conditions. These wads are made from compressed wood materials, with paraffin wax as a binder to give added strength. Plastic wads are also a problem, especially in areas where they could be ingested by livestock. Research into the use of photodegradable wads, which have a limited lifespan when exposed to outdoor elements and sunlight, is ongoing. Plastic wads have a UV light stabiliser to give longevity, but photodegradable wads have this stabiliser removed or reduced, which allows them to break down into smaller pieces within a few weeks when exposed to sunlight.

Non-corrosive primers and progressive burning propellants are also the subject of continuing research in striving for more efficient and cleaner performance. Numerous overseas manufacturers, particularly in the UK, regularly select random cartridge samples from batches on their production lines and submit these for chronograph, pressure and velocity testing sometimes twice a day (morning and afternoon). Some have their own testing tunnels, but also send check samples to various proof houses. Some do tests of the loading machines for dosage rates of both powder and shot on an hourly basis. Velocity is measured at 2,5m and 10m from the muzzle and a ballistic analyser is used to calculate velocities. In this way, the quality of cartridges can be monitored and improved on an ongoing basis. Based on this research, UK and other manufacturers have a preference for single-base nitrocellulose powders in which the burn rate is determined by the surface area of the flake. For example, a larger flake area burns faster for light weight charges, whereas a smaller flake gives a slow burn used for heavier weight charges or smaller calibres where pressure build-up is rapid.

American propellants mainly use double-base nitrocellulose powder with an element of nitroglycerine added to it. This allows for a more energetic burn, but a dirty one, leaving residue in the barrel. An advantage of this propellant is that it is more stable in extreme temperatures.

The next time you load a couple of cartridges into the chambers of your favourite shotgun, spare a thought for the difficulties faced by early-day shooters and give thanks for the hard work, research and innovation that make our shooting today easier, safer and trouble-free.

Written by Neil Harmse

Chapter 20. Understanding The Shotgun

New shooters being introduced to the shotgunning sport may find the many terms and techniques rather confusing, with words like ‘load’, ‘bore’, ‘gauge’, ‘choke’ and others bandied about by more experienced shooters without explanation. Let me attempt to clarify these terms.

The sporting shotgun is usually of three types: firstly, the double-barrel, either side-by-side (s x s) or over-and-under (o/u) configuration. Secondly, there is the single-barrel, singleshot and thirdly, the single-barrel, multi-shot, either pump (or slide) action, or auto- (self-) loader. Just to muddy the waters, there is also the combination, which is a shotgun barrel (or barrels) with a rifle barrel. These are more popular in Europe than in South Africa.

Most sport shooting or field sports favour the double-barrel, with the over-and-under design being more popular nowadays. The side-by-side version is more traditional and there are many shooters, especially the older generation, who still prefer this style. The side-by-side usually has a slimmer, sleeker action and is lighter to carry and use over long periods in the field than the over-and-under. These are ideal for waterfowl and terrestrial game bird-hunting.

Because of the barrel configuration, the over-and-under has a deeper, bulkier action, is heavier and is therefore able to withstand heavier loads or charges than the side-by-side. This allows it to contend with more sustained shooting volumes, such as done in clay target-shooting.

Double-barrel guns come in two main action designs. The box lock is a shorter action and appears more truncated at the rear, with its strikers, springs and working parts all housed inside the action body. Box locks are easier to manufacture and generally more robust. The side lock is more intricate and labour-intensive to manufacture, with its firing mechanisms and springs individually pinned to separate side plates extending rearwards behind the standing breech of the gun. These side locks provide extended flat outer surfaces to allow for extensive engraving, especially scenic engraving, making them a popular choice for best-quality guns. However, this is not to say that the box lock is in any way inferior.

A side-by-side shotgun with sidelocks.

An over-and-under box lock shotgun.

American sportsmen generally favour semi-auto and pump action guns for waterfowl and upland bird-shooting, but in the UK and South Africa, these are not readily accepted in shooting circles. This is mainly for safety reasons, as a double is visibly safe when the action is open, which is not the case with a pump and auto-loader. These have magazines which can normally take about five cartridges, but in terms of South African regulations, they must be plugged to accept only two rounds. Multi-shot pump guns are mainly used by law enforcement and security services in South Africa.

Just a point on safety: I remember an incident where a group of us were on a bird shoot. One of the party was a man of continental extraction, who was using a semi-auto shotgun. We had returned to the vehicles for a welcome coffee and a sandwich and noticed that his gun was leaning against the car with the action closed. When asked if it was unloaded, he assured us that it was, and promptly picked it up and pulled the trigger. With a loud bang, a shot went off, fortunately into the air.

Everyone was shocked, not least the owner of the gun. Needless to say, he was never invited to a shoot again. This just proves the point of the danger of semi-auto and pump action guns.

Barrel length is a matter of purpose and personal preference. There is a common misconception that the longer the barrel, the further (or harder) the gun will shoot. Longer barrels are solely to add muzzle weight for balance and ‘swing’. Common sporting barrel lengths are 25-30” (63-76cm), with 28” (71cm) being the most versatile for all-round use. Dedicated clay target-shooters normally opt for longer barrels. In my experience, barrels of 30-32” (76-81cm) appear to deliver a downward muzzle ‘flip’, while barrels of 25-27” (63-69cm) seem to give an upward ‘flip’. The 28” barrels are more stable, with no significant muzzle ‘flip’.

The distance and spread of the shot charge are determined by the degree of choke, and not the barrel length. It is not clear who first came up with the idea and design for the choke on shotgun barrels to give various spreads of pellets, but it is known that Alexander Pape first patented the design in England in 1886. Thereafter, WW Greener went on to improve and develop chokes on his guns. The choke is the constriction within the last section of the muzzle which concentrates the shot pellets. A full choke has a tighter constriction and gives a tighter pattern, resulting in denser shot patterns for longer range. True cylinder means no restriction at all, allowing the shot to spread more widely after leaving the barrel muzzle. 100 The most popular and versatile chokes for all-round shooting are improved cylinder for closer shots and modified choke for longer shots. Many modern guns come with a set of normally five interchangeable screw-in choke tubes, rendering the gun suitable for any type of shooting and range required.

The term ‘bore’ is derived from the age-old English tradition, whereas ‘gauge’ is an American term meaning the same. The bore or gauge of the barrel is calculated from the number of pure round lead spheres or balls of equal size which fit through the barrel and which, together, would weigh 1lb (454g). Where 12 balls of 0,729” (18,5mm) diameter (the diameter of a 12-bore barrel) weigh 1lb, the gun is a 12-bore. Twenty smaller balls of 0,617” (15mm) diameter would denote a 20-bore gun. Obviously, the numerical bore designation increases as the bore becomes smaller. Nowadays shotgun bores or gauges for all practical purposes are mainly 10-bore, 12-bore, 16-bore, 20-bore and 28-bore, which are popular sizes. An exception is the .410 shotgun, which is not a bore designation, but is a calibre and is the actual barrel diameter measured in inches.

Chamber lengths also deserve a measure of understanding. Many older guns (roughly pre-WWII) have chamber lengths of 2½” (65mm) and longer cartridges must not be used in these guns. They may seem to fit into the chamber, but when they are fired, the crimp opens into the forcing cone, which is a restriction ahead of the chamber at the start of the actual barrel. This can cause raised pressure to dangerous levels. Most modern guns have chambers of 2¾” (70mm) and some guns may be chambered for magnum loads of 3” (76mm).

Let us have a brief look at cartridges and loads. (These will be covered in detail in a following chapter.) Today most shot cartridges have a metal case head (base and rim) and the walls of the case are made of plastic with a fold or ‘star’ crimp at the mouth. Varnished paper cases are available for those traditionalists who enjoy the nostalgia of shooting vintage-type loads in vintage guns. Pellet size in game bird or clay target loads is usually numbered from number 9 shot, which is small (2mm) to about number 3 shot (3,3mm) or even number 1 shot (3,7mm). The larger pellets are usually used for hunting geese and larger birds. There are tables available showing recommended shot sizes for use on various game birds. As a rule of thumb, 8, 7½ and 7 are usually used for clay target doves and pigeons, 5 and 6 for terrestrial game birds and duck, and 3 and 4 for geese and waterfowl. Generally, 5 and 6 shot sizes are a good all-round compromise. Shot loads are normally shown in grams, being the weight or mass of pellets in a load. A 28g load (1oz) of number 6 shot would have about 270 pellets in the cartridge. Most game loads are 28-32g, with 34g being a heavier game load. Obviously, the bigger the shot size, the fewer pellets will be in the load. It is generally acknowledged that pattern kills, so the more pellets striking the bird or target, the higher the chance of a kill. Larger pellets mean less dense patterns and a higher chance of a lost bird. Until recently, most modern cartridges had a plastic cup wad enclosing the pellets, which effectively improved shot patterns and reduced bore leading. Nowadays, though, many game loads are being loaded with biodegradable fibre wads, which are environmentally friendly, but open the patterns somewhat.

Much is said and written about being ‘gun-fit’. Unless you are sufficiently well-off to order a bespoke gun made to fit your personal physique, you will have to make do with the ‘average’ gun off the shelf. Fortunately, most leading gun manufacturers have done much research into the measurements of the average person and the guns are manufactured by CNC process to fit most shooters, without much alteration.

The most common problem with a gun off the shelf is stock length (length of pull). This is measured from the front surface of the trigger to the rearmost centre of the butt-plate or recoil pad. If this is too long, it can be shortened by a competent stock-maker by cutting a slice off the butt end of the stock. If it is too short, the stock-maker can add a spacer or thicker recoil pad to lengthen it, depending on the length of your arms and neck, as well as your shoulder width. Most other problems of fit can be adapted or corrected by good gun mounting and style. Muscle memory is wonderful and by ‘fitting yourself to your gun’ and continually practising correct gun mount, your shooting will improve dramatically.

A wise shooter once said: ‘Shooters will improve their shooting by using a gun with a shorter stock, more open chokes and a shorter barrel.’ Whichever gun you use, go to a shooting range and have an instructor check your hold, style and mount. Once you feel comfortable and know the right moves, stance and mount, go home and practise these over and over. Standing in front of a mirror can help. (Please make sure your gun is unloaded before you do this!) For dry-firing, invest in a good set of snap-caps or dummy cartridges, which will prevent firing pins or strikers from being damaged.

As with any expensive piece of equipment, a gun should be cleaned and oiled after use during the shooting season, and at least once or twice during storage in the off-season. A good cleaning kit and gun oil are essential for the maintenance of your firearm. There is a trend among some shooters of simply pulling a bore-snake (pull-through) through the 102 barrels after a shoot and then putting the gun away. This is highly inadvisable. Although the barrels may seem clean when one looks down them, there will be powder and lead residue which are not easy to see and could cause corrosion or damage. I suggest using a rod, brush, patches and woollen mop to give the barrels a thorough cleaning, followed by a light coat of oil. Wipe all the metalwork with a lightly oiled cloth. Do not spray a lot of oil into the action or barrels. Light oiling is all that is required, as too much oil is also detrimental, especially to the stock and wood. Use a cotton bud or small art-painting brush to get into the inner parts of the action and fore-end mechanisms to remove grass seeds, dust and other debris. Remember to oil under and around the safety catch. If sweat and moisture get under this, they can cause rust and seize the catch. Lightly wipe the wood with a good stock oil or stock wax once or twice a season, especially in wet weather, and again before long-term storage. A good idea is to wipe a light coating of petroleum jelly along the junctions of the wood and metal around the locks and action to prevent moisture or rain from getting into the action. When storing my guns in a safe, I enclose them in a good silicone oil-coated gun sock such as ‘Sack-Up’ or similar and then stand them muzzle-down to allow any excess oil to drain downwards to the barrels, rather than soak into the wood. Never store guns in a bag or case, as this may cause them to ‘sweat’ and rust.

Looking after your gun in this manner will ensure that they give trouble-free service for your lifetime and that of the next generation. Many guns well over 100 years old are still shooting as well today as the day they left the gun-maker’s bench.