Often and willingly we talk about gauges and chokes, but not everyone has clear ideas about it... let's elaborate some more on that also thanks to the support of Prof. Simone Bertini, one of the top hunting experts.
On this first date we will take a journey into the history of gauges, with some information pills for each of them.
The “gauge” in hunting weapons has always been the subject of numerous discussions and sometimes of conflicting opinions; how many times have we heard, in fact, that “the gauge 12 is all hunting”, “the gauge 20 is the best there is for migratory”, “the gauge 16 is the ideal solution”, “the gauge 28 is the best”, “the gauge .410 is a sports gauge”, and so on. We are obviously talking about smooth-bore rifles, because we are going to leave out the calibres for striped weapons.
However, what does the word “gauge” really represent? We could answer that the gauge indicates the inner diameter of the barrel expressed in a unit of measurement, be they tenths of an inch, millimeters, but not in the case of smooth-bore shotguns. In the latter the English measurement was conventionally maintained, which was quite particular. Basically, the British indicated the gauge with the number of spherical lead balls that had the necessary diameter to be fired from the same barrels. On top of that, the balls had to be obtained from an English pound (unit of measurement that equals to 453.6 grams), bearing in mind that – depending on the country – the weight of the pound could differ slightly. A 12 gauge indicates that 12 lead balls could be obtained from the pound, while a 20 gauge could have a barrel capable of firing 20 lead balls obtained from the same pound. And so on for the other gauges; we are therefore witnessing a paradox, in which the increase in the numbering of the gauge (from 12 to 28, for example) corresponds to a smaller gauge. Warning: what we have just said does not apply to gauge .410, as the latter indicates the diameter of the bullet in inches. This gauge is therefore an exception in the weapons scene and in the classification mode.
Equally obviously, from the number of balls obtained from a pound, it is possible to trace the nominal diameter of the barrel itself through a formula; when we talk about the diameter in the core of a barrel, we mention the diameter that the manufacturer has considered appropriate to use, while remaining within the variability granted by the CIP standards. Just by way of example and indication, a 12 gauge barrel can range from a minimum of 18.1 mm to a maximum of 18.9 mm; a 16 gauge barrel from a minimum of 16.80 mm to a maximum of 17.20 mm; a 20 gauge barrel from a minimum of 15.80 mm to a maximum of 16.1 mm; a 28 gauge barrel from a minimum of 13.9 mm to a maximum of 14.4 mm; a 36 gauge barrel from a minimum of 10.40 mm to a maximum of 10.8 mm.
In a few lines we will talk about the hunting use of the various gauges, giving some examples to tickle your curiosity; but first we still want to focus your attention on the choke, also because the hunting action itself is often and willingly conditioned in the positive or negative sense by a correct choice. The smooth barrel has undergone – at the beginning of its history – several attempts at modification to increase the useful range of the pallets or in any case to obtain the best possible yield; the first barrels were in fact very long, much longer than we are used to seeing today, at least for hunting purposes. Over time these beliefs faltered, to the point that they went from one extreme to the other, with the English gunsmith Churchill who advertised the 25-inch barrels enormously, that is 63.5 cm! A lot of books written by him, tells of the advantages deriving from the use of a short barrel compared to a long barrel. In fact, it can almost safely be said that with modern construction materials, there is no oversized difference in the ballistic performance of that barrel, especially with regard to its length. The important thing is that there is sufficient length to allow the propellant contained in the cartridges to burn properly.
It was the advent of the chokes that changed the ballistic yield of the barrels; after the first attempts of Pape, the brilliant English gunsmith W.W. Greener was the inventor of the modern choke; essentially, the cylindrical barrel was choked at the mouth, which increased its effectiveness on the wild, as demonstrated by the numerous experiments conducted and published at the time. Thus, the introduction of the choking into a smooth-bore hunting shotgun, first applied in a fixed manner on the barrels and then later declined in the varied world of interchangeable chokes, had taken place. Nowadays practically all commercial/industrial shotguns are designed to accommodate interchangeable chokes, leaving only a few particular and customized weapons with the choice of a pair of fixed chokes. A river of opinions has been spent to understand if the barrels with fixed chokes are preferable to those equipped with interchangeable chokes, but it has become a trivial matter; as mentioned, all modern barrels are equipped with a set (more or less complete) of chokes, which has increased the hunting potential beyond measure.
The modern chokes, made of high quality steels and even in noble materials (titanium alloys) have internal geometries that have nothing to envy those solutions that were proposed by gunsmiths and gunners, where their expertise compensated for construction deficits still undeniably present in the last century. The standardization of industrial processes, together with a construction virtually devoid of mechanical tolerances and scientific studies on the distribution of the pallets (viewable with very powerful cameras and slow motion), allows to have accessories that become an integral part of the shotgun and in particular of the barrel, exalting each other. Not to mention the technological advantage offered by a good set of chokes, the hunter/shooter can easily change hunting scenario in a few minutes, completely changing the ballistic performance of his barrels and his shotgun, of any gauge. On the contrary, the adoption of interchangeable chokes has exalted those calibres that until a few years ago were relegated to small bird calibres, good only for "sheds" and that instead have known – since the end of the 90s – a huge success in the public and sales. To the point of moving from the meaning of children's shotguns to "non plus ultra" shotguns as far as ballistics are concerned.
We wanted to summarize in a few words more than a century of history and important attempts, which have in fact revolutionized the shotgun with a smooth core. And, mind you, we have not even in the least addressed the problem of the construction materials with which the barrels were made, because it is not the purpose of this article, even if we intend to try to impassion also on this interesting topic.
Less than ever we have addressed the problem arising from the loading (both industrial and artisanal) of the 28 gauge cartridges and particularly the .410 gauge, where the common user's belief that there is no risk in misstepping doses is completely incorrect and even very dangerous, precisely because of the very structure of the small gauge cartridges. These will be topics to which other...insights will be devoted, starting from the next one which we will go on the field to analyze the woodcock and the sedentary game!