The ubiquitous 12-bore, due to its immense popularity, has become the standard against which other gauges are judged. The twelve is regarded as a versatile all-rounder, something of a jack of all trades. Using ultra-light loads, it can be employed in a similar way to a 20-bore. At the other end of the scale in the long 3½in chamberings it is similar to 8-bore loadings. In spite of this apparent versatility, however, there are still enthusiastic goose shooters prepared to shoulder mighty wildfowling pieces and gameshooters who prefer to use smaller guns such as the 20- or even 28-bores when shooting driven game.
Pushing your loads
Problems will arise with any gauge of gun when loads are pushed to the limit. Larger than normal shot loads generate more recoil and long shot strings. A long shot column can produce a large percentage of deformed pellets from contact with the bore (unless plastic cup wads are used), which contributes towards poor shot patterns. Very light loads can also tax the ammunition manufacturers ingenuity when it comes to obtaining good patterns, and sometimes it seems there is a bit of instinct involved as well as the ballistic science.
It is, therefore, no coincidence that we have guns of different bore sizes, which evolved originally to use shot loadings appropriate to the gauge in order to produce the best all-round performance. Also, ideally the gauge, shot load and shot size should be matched to the anticipated sport, though there have always been fine Shots successfully using small bores. And now that there are increasing numbers of shooters using very small-gauge guns as a challenge, how do they fare?
Performance comes down to good patterns of suitable shot density and pellet energy, or what might be called striking power. Velocity is a component part in the production of pellet energy, but in recent years too much emphasis has been placed on this factor, though it is valued by clay pigeon shooters. There is a considerable difference between breaking a comparatively fragile clay with small shot, where pellet energy is not especially important, and penetrating feathers and muscle of a bird or cleanly bowling over a running rabbit or hare. Excellent patterns at reasonable velocities usually give the best all-round results and it is no coincidence that, as velocities are pushed ever higher, it becomes more difficult to hold patterns together.
Small-bore enthusiasts that is, those who like anything smaller than 16-bore will sometimes argue that smaller gauge guns throw proportionally tighter patterns and therefore tend to hit harder. This is based on the idea that because the shot column in a smallgauge gun already occupies a smaller area it will not expand as much as that of a larger gun. If this was correct it would mean that a 28-bore would throw a pattern about half the size of a 12-bore. It is a seductive idea, but one that is unfortunately not true.
Testing the theory
To prove this point, I set up a simple test to compare pattern sizes and shot densities. Using a 12-bore as the control standard, it was compared with a 20- and 28-bore and, at the other end of the scale, a light 4-bore muzzle- loader. For the breechloaders shot loads were chosen not only as appropriate for the gauge, but also on the basis of what was readily available at the local gunshop. All loads used No 6 lead shot, as this is the choice of a great many gameshooters.
The distance for testing was 30 yards since this is a reasonable distance from which shots might be taken in the field. For each shot the overall size of the pattern was measured with due allowance for the odd flyer and results took into account that not all shots would necessarily be central on the pattern sheet due to gun fit differences.
Table 1 shows what gun and cartridge makers have known for years that small-gauge guns do not shoot obviously smaller patterns. What you actually get is a similar spread of shot based on the choke being used, meaning a lesser amount of shot to fill the same piece of sky when compared with a larger gun.
Next we tested for pellet counts (number of pellets in a 30in circle) at 40 yards the maximum distance at which most gameshooting is undertaken(see Table2). As far as pellet count is concerned, if you prefer small-gauge guns, there is no doubt that you are putting yourself at a disadvantage. It is better to use a smallbore that fits rather than a 12-bore that doesnt and as a consequence fails to throw the shot where your eyes believe it should be. This is of little consolation, however, when you consider that a 28-bore with 16g load has about half the number of pellets of a 30g 12-bore load to do the same job.
The options, therefore, would seem to be either to increase the shot load, in which case you might as well have a bigger gauge gun for sweeter shooting, or go for more choke to increase the pellet density. The tests indicated that you should not use even a full-choked 20-bore(with the test loads)at distances considered too far for a half-choke 12-bore, especially where full-choke in the latter might be more appropriate. Similarly, a fullchoke 28-bore would struggle to match a cylinder bored 12-bore for shot count. Using more choke brings the shot closer together increasing its effectiveness but reducing the spread of the bulk of the shot charge for any distance and requiring better marksmanship.
Implications in the field
Small-bore guns are delightful and do have their place on the shooting field. But it does mean that you have to be a good Shot, and for anyone having difficulty connecting with a 12-bore, changing to a smaller gun is only likely to make things worse. Also, what is calculated theory and shown on the pattern sheet does not always exactly match what happens in the field, where circumstances are much more uncontrolled. However, it would seem, on the results obtained, that for fairly close driven game such as partridge, the outstandingly good Shot could successfully use anything from 12- to 28-bore, but this does not alter the fact that a bigger gauge will always have the edge in real performance. When faced with super-high pheasants that even begin to tax the performance of a 12-bore, the 20-bore user will be struggling to produce adequate patterns. Then there is always the increased potential for wounded birds. If high-bird shooting is envisaged, then there can be no doubt that the 28-bore should be left in the gun cabinet.
So, for the average shooter, a good big gun will always be a better bet than a good little gun. If you wish to kill things convincingly, use a 4-bore, but the 12- and its close cousin the 16-bore will do most of what you need. The 20-bore is not so far behind for many uses, but those little 28s do need to be used with care. We owe that much to the quarry.