That Shot-String Thingby Peter F. Blakely
From Successful Shotgunning, By Peter Blakeley;
Reprinted by permission of Stackpole Books
Have you ever seen the Tour de France cycle race on the sports channel, where hundreds of perspiring guys pit their physical capabilities against the grueling, undulating terrain of southern France? Sometimes the top guys seem reluctant to blaze a trail for the others and prefer to lag behind the front-runners. What they are doing is using the effects of slipstreaming, also known as drafting, by letting the guys at the front do most of the hard work. Many years ago, a cyclist set a new world record by riding at speeds in excess of one hundred miles per hour. He did it by utilizing the full advantages of this phenomenon by riding in the slip-stream of a large truck. In nature, geese fly in V formation for exactly the same reason: the strongest birds in the skein take the lead, while the younger and weaker birds fly behind with less air resistance to fight.
Many years ago, I spent many happy hours hunting ducks and geese on the Solway Firth in Scotland. During a lull in the activity (somewhere in between fumbling with the top of a Thermos flask with frozen fingers and nudging the dog to make sure it hadn’t succumbed to the freezing temperatures), I would absentmindedly watch the huge flocks of Barnacle and Pink-foot geese flying in to the feeding grounds in the early morning. I have often seen the lead gander, buffeted mercilessly by a strong offshore headwind, drop back and change places with the next in command as he tires. So what have Scottish geese and French guys on bikes got to do with shooting? Something known as shot-string effect.
We have seven hundred members at the Dallas Gun Club, so arguments and discussions on the merits of shot patterns and shot-string regularly bubble to the surface. To most of the members, shot-string is one of the topics of conversation that distinguishes the guys who know what they are talking about from the ones who like to sound as though they know what they are talking about. Shooting, and its associated experts (self-professed or otherwise), has always been like that. Most shotgunners know (or think they know) what shot-string is, along with what the effects of shot-string are on successful shotgunning. However, for most of us, it is a huge gray area, and it would not do us any harm to find out more about it.
Because of the slipstreaming or drafting effect, the main concentration of pellets would be in the front portion of the shot-string.
We have ten skeet fields at the club, and directly in front of these, we have a large lake. On calm days, when there is minimal wind and the surface is like a mirror, this lake has a practical use, and I like to use it to demonstrate to my students the effect of shot-string. I must stress that there is absolutely no scientific relevance here; it is merely a visual demonstration. As soon as a cloud of pellets leaves the muzzle of a shotgun, the shot begins to spread both laterally and longitudinally and develops into a rough sausage-shaped cloud, which is usually more dense at the front than at the back. The greater the distance from the muzzle, the greater the length of the shot-string. The effect of this "stringing" can clearly be seen if a shot is fired into a smooth expanse of water, and from this demonstration, it is obvious that the charge of shot is three-dimensional.
Taking into account that at twenty yards a pattern from a cylinder barrel will be about thirty inches wide, and that obviously (depending on the angle to the surface of the water) there will be some difference between the arrival of the first and last pellets to hit the surface, there is a visually progressive difference--the pellets seem to "run out" along the surface. Wayward pellets and "flyers" can clearly be seen as the pattern hits the surface of the water. It is rumored that Lieutenant Colonel Sir Peter Hawker, "the father of game shooting;’ often used the fast-flowing river test (which would obviously give a better visual demonstration than my expanse of still water), using a river that ran past his ancestral home, for similar demonstrations almost two hundred years ago. It was mentioned in his book, Instructions to Young Sportsmen in All That Relates to Guns and Shooting, written in 1814. However, apart from this visual demonstration, there is also an audible one. When shooting from a distance at a steel pattern plate with different loads, there is an obvious audible difference between the impact of the first pellets arriving at their target and that of the last pellets. So what causes this, and how can it affect our performance? Perhaps more importantly, is it beneficial to our shooting in any way and in what respect?
Many shotgunners genuinely believe that there is a huge advantage to a long shot-string, and I have been involved more than once in (sometimes heated) discussions concerning the advantages and disadvantages of degrees of choke and the resultant long shot-strings. We all know, for example, that a tight choke gives the advantage of a longer shot-string, doesn’t it?
Afraid not. What barrel constriction will give is better pattern density, not a longer shot-string. We also know that the first pellets to leave the muzzle of the shotgun will be the first to reach the target, right? Wrong again. Finally, we all know that it is possible to influence the length of the shot-string by the speed of the swing, the sort of jet-of-water-from-a-hose effect, don’t we? One of the members was quite insistent that on an overcast day, he could see a "bend" in the shot-string, which was a result of him using a fast gun swing. He is not alone.
Many people genuinely believe this. Well, can they? Does the stringing effect of the shot start to occur inside the barrel? Once again, simply not true. This effect is an erroneous mental picture and is easily explained. The shot column may be only an inch long as it leaves the gun. The difference in the time interval between the front of the shot column exiting the barrel and the back may be only less than 0.00005 of a second, during which time the gun barrels would have hardly moved, so there is no advantage regardless of how fast the gun is moved.
Extensive tests on the efficiency of gunpowder, the effects of choke, and also patterns, penetration, and shot-stringing were carried out at the public gun trials in London as far back as 1859. These gun trials were carried out at intervals in 1866, 1875, and 1879. Similar trials were carried out in America-the New York trials of 1873 and the Chicago trials of 1874 and 1879. Many of the tests at the London Gun Trials of 1879 were carried out by Mr. R. S. Griffiths, who was the ballistics expert for the Shultz Powder Company. Until Griffiths’s experiments, the physical properties and effects of the shot-string were a mystery.
Griffiths realized that although shooting a charge of shot at a pattern plate would give a reasonable indication as to the density and effectiveness of the pattern at a specific distance, what it failed to do was give any indication of which of the pellets arrived first and which arrived last. The simple pattern board would not show the overall effect of shot-stringing. Two pellets on the pattern board may be only an inch or so apart, but in reality, as they traveled through the air, they may have been six feet apart or more. Griffiths carried out experiments that involved shooting at a stationary paper target, behind which there was a rotating circular target that was twelve feet in diameter. This target revolved at a specified number of revolutions per minute, and by shooting at this combination of static and revolving targets and then by comparing the two, Griffiths could measure with reasonable accuracy which pellets struck the target first and which struck last. The results of his tests were published in The Field magazine and later in Land and Water.