Shotgun shells explained - a case study

Paul Miller

The shotgun shell as we know it today has evolved since its invention around the 1860s into a sophisticated and effective cartridge that covers a whole world of uses at relatively short range. Originally they looked much like a brass rifle or pistol case with straight walls and various methods of holding the overshot wad in place to keep the lead pellets securely in the cartridge.

Somewhere around 1880 paper hulls started to replace full brass shotgun shells mainly because of economy, and this method of construction with a brass head to accommodate the primer was popular right up until the late 1960s world-wide.  

In the early days felt wads were used to separate the powder in the base of the shell from the lead shot payload. The shell was finished off with a cardboard over shot wad and the shell roll crimped to keep the shot in place. As time progressed these paper shells were elongated and the forward section beyond the payload crimped and roll finished to replace the older methods of sealing the shell.

In the late 1970s there was a short-lived trend in shotshell construction with a move to all plastic cases with a small brass ring moulded in the primer area to provide support for the primer. Today almost all cartridges are plastic constructed but with low or higher brass bases. Putting it simply, low brass suggests lower pressure loads and high brass for high pressure loads.

While high brass supporting the plastic case does not actually provide much more strength it does allow shooters to easily differentiate between cartridges. There is also a little hype in this or perhaps a confidence factor, with high brass shells invariably used in manufacturers’ more expensive higher performance loads. I’m generalising here but I’m sure you understand what I mean.

Just because a shell has a high brass case doesn’t mean it is any more powerful than one with a lower brass base. The height of the brass has nothing to contribute nowadays to the power of the shell or the speed of the payload. There are some field loads, especially in England, which are still loaded in paper and brass cases with felt wads for biodegradability but the majority of shells nowadays are plastic and brass with plastic wads.

The problem with felt wads is that they don’t protect the shot as it travels up the barrel, damaging the outer layer of pellets in contact with the much harder steel barrel until the payload leaves the barrel. This results in wider patterns compared to the shot being protected inside a plastic wad cup and never coming in contact with the barrel. This means less damage to the shot column and this reduced deformation means tighter patterns because round shot fly much more true than damaged non round shot.

Shotgun shells are measured by gauge, which is the weight in fractions of a pound of a pure lead ball that is the same diameter as the internal diameter of the barrel. A 12-gauge shotgun which we mostly use in Australia is measured by a pure lead sphere that just fits inside the barrel and weighs 1/12th of a pound. Hence the name ‘12-gauge’. A 20-gauge has a smaller diameter barrel and requires 20 pure lead balls of the diameter of a 20-gauge barrel to weigh 1lb. Even lighter shotshells like the 28-gauge follow the same principle. The .410 ‘snake gun’ we often refer to affectionately in Australia is not a gauge but is measured by diameter of the barrel ‑ ie, .410 of an inch.

Shotgun shells nowadays, as we’ve already noted, are mostly made up of a plastic and brass case and a payload. They require a primer to set off the powder and today we mostly have plastic wads that contain the lead shot and which provide an excellent gas seal to allow the powder to burn effectively and create the explosion and expansion that almost instantaneously forces the payload to accelerate up the barrel.

The wad not only separates the powder from the shot but the middle bit of the wad is called the cushion and this acts like a shock absorber both in terms of recoil and protecting the shot from deformation by slowing fractionally the effects of the powder exploding and accelerating the wad and shot up the barrel. When the wad exits the barrel, there are usually four slits in the plastic shot cup that help the petals to open and this causes the wad to quickly fall away as the shot goes on its way to the intended target.

Modern shotgun shells are used for a great many purposes but for the intent of this article let’s stick with hunting and clay target shooting.

The target dictates the size of the shot. For skeet shooting at clay targets we usually use 70mm (2¾") long 12-gauge shells with 24- or 28-gram loads of very small 8 or 9 shot. These are most popular because they have a huge number of tiny pellets which when combined with open chokes fill out a wide pattern and increase your chances of breaking these fast, closer range targets. The 20-gauge are also popular for clay shooting but their payload rarely exceeds 24 grams with the occasional 28-gram load available.

For longer crossing or departing clay targets we usually use 28 grams of 7.5 or 7 shot through tighter chokes. These individual pellets hit much harder but there are a lot less pellets in a load of 7s compared to 9s. It is about (290) 7s compared with (585) 9s in a typical 28-gram target load. I tend to mainly use 7.5s or 8s for all my clay shooting so have about (350) 7.5s or (410) 8s in my shells. These deal emphatically with any clay thrown within sensible shotgun range subject only to clever manipulation of choke constriction and putting the pellets in the right spot to break the target.

With shotshells used for hunting we see many fewer larger pellets in 28-gram loads and so the tendency is to use bigger gauges and payloads. An example of this would be the use of longer 12-gauge shells with 76mm (3") long cases and payloads varying from 32 to 42 grams. These are what are referred to as magnum loads and should only be fired in 12-gauge shotguns with 3" chambers. These cartridges have a lot more recoil because they are pushing much more shot up the barrel at similar speeds to the lighter clay target loads.

Typical hunting loads may vary from one solid rifled slug for pigs or deer to classics like 00SG buckshot with nine copper-plated lead pellets in a 2¾" load or 12 of the same pellets in a 3" case. Winchester makes these loads available in Australia as well as the traditional Buckshot which has 18 smaller pellets in a 2¾" case. These are potent shells shot through tighter chokes at closer ranges that keep sufficient pellets in the pattern to do the job on bigger game that you would otherwise use a substantial centrefire rifle to take humanely.

In more recent years, especially in the US, there has been laws passed where shells must be loaded with steel pellets initially for hunting, especially over swamps where game birds are said to pick up lead pellets on the bottom of the pond or waterway when they are feeding and thus suffer lead poisoning if enough pellets are ingested. This trend has also entered the clay shooting world in some countries where steel loaded shotshells are mandated for all shotgun shooting. This is seen as a more environmentally friendly alternative to lead.

There is still much debate about this because of the different ballistics between these two pellet materials. Lead is heavier per pellet and so more ballistically efficient and harder hitting on the target than the same size steel pellet. This means that to obtain the same killing power with steel shot you need to use larger pellet sizes and this means a lot less pellets per comparable load when using steel shot. This in turn means less dense patterns and the possibility of game slipping through the thinner pattern or just being wounded because the game bird, rabbit or fox is not hit by sufficient pellets to ensure a clean and merciful despatch.

The other alternative is to use a larger space to accommodate a lot more steel pellets to equal the same weight of the lead load. Sometimes there is not sufficient space in a standard 2¾" or 3" case to end up with steel loads that match comparable lead shot loads. A lot of work has been done in this area to make steel loads as effective as lead but for many the jury is still out.

The other issue with steel shot is the need to ensure your shotgun is steel proofed. This means the manufacturer has used a high-quality steel in their barrels that is harder and compatible with steel shot. Chokes also behave differently with steel shot and the usual recommendation with steel shot is to restrict yourself to a maximum choke constriction of Half Modified choke even if the gun is steel proofed. Because the pellets are much harder, they tend to pattern tighter at reasonable shotgun ranges but the other thing to remember is that their hardness also leaves them more prone to ricochet off hard surfaces. The other drawback with steel versus lead is cost. Steel shot is a lot more expensive to produce and this is reflected in the considerably higher cost of steel loads.

I’ve always been interested in reloading shotgun shells to achieve particular objectives. In recent years I have given up reloading competition clay target shells because they can be bought in bulk at prices about comparable or less than reloading. When you factor in all the equipment and components and time required to reload large numbers of shells for clay target shooting it’s not worth the effort unless you enjoy the process and delight in breaking clays convincingly with shells you have loaded yourself.

The cost of field loads on the other hand are expensive and if you do a bit of game shooting it is not so hard to rationalise reloading these shells with heavier loads of fewer larger pellets for whatever particular game you are hunting.

When I started reloading I noticed there were different powders available for different purposes. Faster burning powders like Hercules Red Dot were recommended for clay target loads especially as you used less quick burning powder than slower powders to achieve the same result and this was something of an economy when shooting hundreds or thousands of shells a year.

In my day the standard load for Trap and Skeet was 32 grams or 1 1/8oz. These loads could be bought with speeds anywhere from about 1150fps to 1400fps and the faster ones really booted. A day shooting these and you felt like your teeth were going to fall out. An end of day headache and sore shoulder were inevitable.

Slower burning powders like Hercules Blue Dot were available for magnum field loads which meant more shot could be moved along but with reasonable levels of recoil. The fact is that you don’t normally shoot as many loads field shooting in a day as you do clay target shooting so recoil is often not noticed in the excitement of the hunt or where only a few shots are taken on the day.

In my early days I thought it would be great to have a clay target load that was fast but didn’t kick. This seemed like an impossible dream until I did some research in American and English publications and reloading manuals (no internet at that stage) and developed some loads that were not available in Australia 20 or so years ago.

I achieved this by loading 28-gram (1oz) loads using 8 shot rather than 7s because my research revealed that I had almost exactly the same number of 8s in a 28-gram load as I did 7s in a 32-gram load. The 28-gram load was fully 1350fps compared to the 1250fps of the 32-gram load. I also found that by using the slightly slower Green Dot powder of the time rather than Red Dot that the shells recoiled even less and had a smoother feel about them.

For closer targets I applied the same theory and used the same 1oz wads I’d managed to source to create 24-gram loads and used 9s and had a heap more pellets in these even lighter loads than the 28-gram 8s. They smoked Skeet targets and closer sporting clays and were every bit as fast and even easier on the shoulder. Today all these loads are available commercially but it was an enjoyable learning curve and I shot some of my best scores ever with my reloaded 24- and 28- gram loads.

The humble shotgun shell is actually a clever type of ammunition designed for close-range work on any game animal or clay target competition known to man. It’s just a matter of picking the right factory load or loading responsibly to gain exactly what you want for field or competition use. In combination with intelligent choke selection the modern shotgun shell is up to any task.

Today you can walk into a well-stocked gunshop and buy factory loaded shotshells for any purpose. There are bulk buys for slabs of 250 competition shells and any number of hunting loads in boxes of 25 cartridges. There are specialised hunting loads including solid slugs with rifling built into the projectile in packets of five or six and these are the most expensive of all per shell.

For the reloading enthusiast there are all the components including primers, powder, wads and shot of all sizes to suit your purpose.

You will need to invest a considerable amount to buy quality reloading equipment and then study up on safe reloading practices to produce shells that will give you a huge amount of satisfaction when you shoot them successfully. You will also have the benefit of increasing your knowledge of shotgunning enormously by taking this route.

This article barely scratches the surface of the world of shotgunning but clay and field shooting has provided me with half a lifetime of incredible enjoyment that I’ve shared with my like-minded mates. Long may it continue for all of us who are proud to be responsible shooters whether it be with shotgun or rifle.

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