Chapter XI: Chokes, Patterns, and Velocities

Boring shotguns has reached its present state of perfection, if we are permitted to call it such, through a process of evolution. A decade or so ago all sorts of artifices for throwing shot in a closer mass were called chokes, though some of them meant a freeing of the muzzle, others a recess or two recesses where the shot charge spread and was then contracted. There were recess-chokes, bell-chokes, multiple-chokes, jug-chokes, and at last taper-chokes. Some of these styles were fairly effective, others were effective temporarily, and others are in use at the present time. To-day manufacturers have settled upon methods of choking their barrels so similar that results in all our best arms are practically equal.

Many gunbuilders claim that their barrels are a true taper-choke, the natural inference being that the bore tapers evenly from breech to muzzle, depending for close shooting qualities upon the gradual contraction of the charge. The theoretical taper-choke appeals to the gun buyer who does not like the idea of suddenly upsetting and jamming his charge with a probability of leading his gun. Theoretically the taper-choke is perfect, but I doubt if it would work at all in practice, and neither have I ever been able to find a gun that had it despite all the claims of manufacturers.

My own belief is that a tube with an even taper from breech to muzzle so that the load could adjust itself as it passed out would shoot little if any closer than a plain cylinder. Choke boring, as will presently appear, depends for its efficacy upon jamming the shot together at the muzzle with such force that they will cling together in a mass for some distance after they leave the gun. A gradual contraction, such as a true taper from breech to muzzle, would not have this effect.

Full choked guns are constricted at the muzzle from twenty to forty thousandths of an inch, depending upon the gauge. As might reasonably be expected, the smaller the bore of the gun the less it will bear being contracted at the muzzle. In the present styles of choking some barrels are bored cylindrical to within a few inches of the muzzle and there contracted, others are freed about the middle of the barrel and thence gradually narrowed toward the muzzle where they have the usual choke. Manufacturers are very reluctant about giving the inside measurements of their barrels, perhaps considering such figures trade secrets.

The writer has often speculated and theorized as to just what process a charge of shot undergoes from the time it starts at the breech until it separates into individual pellets. It would seem, looking at the matter cursorily, that a true cylinder shotgun, sending every pellet from the muzzle in a straight line, with the least possible disturbance of the load, would shoot the closest. So it would, possibly, except that as soon as they leave the muzzle every individual pellet begins turning and twisting, giving every contiguous shot a figurative kick out of the way. They kick one another until they become scattered too far apart, and by that time every separate pellet is going its own course at a distinct angle from every other until when they reach the forty yard target the pattern is six feet across. Indeed I have seen the outer pellets fifteen feet apart at the distance.

Now what is the reason the pellets from a full choked gun do not begin to squirm and kick one another the moment they leave the muzzle? When you have fully decided this point you will know more of the secret behavior of the shot charge of a choke bored gun than anybody has been able to tell us heretofore. Some claim that in some mysterious way when the choke pinches the load together, the shot are set to crossing one another, those lying on the right side of the charge crossing to the left and vice versa. At a certain distance these theorists assert that the pellets begin to cross out and thenceforth the pattern of a choke bore is no closer than that of a cylinder. In support of this “crossing-out” theory they point to the fact that a full choked gun puts perhaps eighty-five per cent. of its charge in a fifteen inch circle at twenty yards which may be reduced to 65 per cent. at forty yards in a thirty inch circle.

Another school holds that the shot charge is elongated in passing through the choke, the forward pellets having their speed accelerated, the shot flying toward the target in a long string in place of a round pattern. It has been proved by the simple experiment of shooting at a rapidly turning wheel that shot do string out as much as sixteen feet in going one hundred and twenty. So positive are the stringing out people of the correctness of their theory that they go so far as to gravely advise the gunner to hold plenty far enough ahead of his game for, if the leading pellets miss, the bird will fly into this sixteen-foot string somewhere and surely get killed.

My own belief is that the pellets from a choked gun do not begin kicking and scattering the moment they leave the tube for the same reason that they would not if enclosed in a concentrator; _they are encased in a leaden shell of their own outer pellets_ which have been dented and welded together by the choke of the gun. The greater the choke in the barrels the firmer this outer shell of shot is welded, and the longer it requires to break up with a consequent closer shooting gun. Let me give some proofs that this theory is at least reasonable and better accounts for the behavior of a charge of shot from a full choked gun than any other that has come to my knowledge.

It is an undisputed fact that every time a charge of shot is fired from a full choked gun thirty per cent. of the load is at once knocked out and rendered useless for the reason that this percentage of the pellets are so dented and deformed that they will not fly true and so fail to reach the target with the remainder of the charge. The longer the range the more erratic the flight of these defective shot and as a consequence the gun falls off in its pattern from fifteen to twenty per cent. These deformed pellets also account sufficiently for shot-stringing since many of them are so flattened as to retard their flight. But this does not mean that the body of the charge, the seventy per cent. of sound pellets, is also stringing and I have no doubt but that they reach the target practically in a body. Defective and misshapen pellets entirely account for crossing and “shooting-out,” the reduced patterns of choke bores at long range, and for stringing of the shot.

Careful experiments have been made by expert gunborers to see if they could not invent some system of choking a gun that would utilize this thirty per cent. of the charge which is now wasted. They were well aware that in case this could be done the twenty bore would become as powerful as the present twelve for the reason that the entire charge would be found in the pattern in place of the seventy per cent. which is now the best that can be uniformly secured. No success has attended these experiments for the reason that this thirty per cent. is the amount of shot necessary to form the shell of lead without which no gun could shoot a choke-bore pattern. From this it is to be inferred that an entirely new system of choke boring will be necessary before this thirty per cent. of waste shot can be rendered available. Should the new system ever come it will be the greatest of all shotgun inventions.

The theory of a lead encased charge being true, it is to be expected that if the gun were given too much choke, or the shot were driven at too high velocity into the choke, the leaden shell would weld too firmly and fail to break up at the proper time or possibly not at all. We find this to be the case exactly. Guns that are over-choked “ball” the shot, a technical way of saying that part of the shell welds so firmly that it will not break up. Costly experiences have so well convinced the manufacturers of this that they now wisely refuse to attempt to turn out a gun choked closer than the usual seventy per cent. It is this welding and balling of the shot also that is now handicapping the gunbuilders in their attempt to turn out high velocity shotguns. If the charge is given a few hundred feet increased muzzle velocity above the present standard, the shot will ball in a choke bore, and the pellets in the opener guns will kick one another so much harder that the pattern is invariably ruined.

It is evident that soft shot would be more subject to the welding process than chilled, and so we find that soft shot are never recommended for high-pressure loads in a choke-bore gun. Granted that it is necessary for a full choked gun to jam the shot and weld a case, then if the shot were so hardened that they could not dent into one another, no closer pattern could be obtained from a choke bore than from a cylinder. Experiments with steel shot have proved this to be an exact statement of the truth for they will not make any closer pattern in a choked barrel than one bored cylinder.

It was supposed that steel pellets might place the entire charge within the thirty inch because none of them would be upset, but instead they scattered like shot from a rifle barrel. What has been said of full chokes applies to any modification, though in less degree.

EVENNESS OF PATTERN

While full choked guns with the closest pattern are necessary for some purposes, as trap shooting and work on ducks, and the development of choke boring has added greatly to the power of all shotguns, yet it is a comparatively simple matter to secure these dense patterns compared with obtaining an even spread of the shot. In this respect gunbuilders have made very small progress this past twenty years, their patterns being little if any more even than those of the old muzzle-loaders.

The diagram shows a forty yard target of 260 shot, that of a modified choke twelve gauge, drawn to indicate what an ideal shotgun pattern should be. Owing to its regularity this modified pattern would be more effective than that of any full choke of 300 shot such as we can now obtain from the most carefully bored guns. Nothing could escape such a shot charge as this from quail to clay birds, and neither would it tear up and riddle the game in the manner of many close shooting guns. Patchy patterns lead to a gun mutilating one bird and missing the next at a like distance, for if one spot has a dense clump of shot another must be open.

Close shooting or density of pattern is a mere matter of correct mechanics, but with our present skill in gunboring uniformity is in a degree dependent on luck, for the most skilled gunborer, cutting his tube to the exact thousandth of an inch, cannot foresee with any certainty that his barrel is going to make an even spread. He can, however, usually much improve the shooting of a barrel by carefully retouching it, but no matter what the experience of the mechanic he can never make two barrels that will pattern exactly alike, and it follows that only on rare occasions is a perfect shooting barrel turned out. This explains why our great trapshots may try fifty guns before finding one that patterns up to the standard they require, and why when such a piece is obtained it is considered invaluable.

The acme of perfection in shotgun boring is to secure an even spread of shot in a close shooting, full choke gun, because, as we have seen, the very principle of choke boring promotes patchiness rather than uniformity. In my own experience I have always had the best luck in securing a regular spread from guns modified a trifle, say those making a target of from 60 to 65 per cent. of the charge. Nevertheless there is no arm that I should appreciate so highly as the full seventy per cent. barrel that uniformly covered the thirty inch circle.

Every new gun ought to be tested and the pattern analyzed before purchasing. The plate shows the method of doing this. Mark off the target into squares of a size dependent upon the game to be killed and diameter of the shot pellets; for quail with number seven and one-half or eight shot, three inch squares, for ducks, four inch. Count three shot as the number necessary to kill with certainty and less as a cripple, no shot in the square, a miss. Analyze several targets and if on the average at forty yards twenty-five per cent. of the squares indicate misses or cripples reject the gun. If you can obtain a gun that will not miss or cripple once in ten shots at the distance it is an extraordinary weapon.

The faults of choke-bore guns are shooting too much to center and patchy patterns. Cylinder and slightly choked guns are apt to throw variable patterns, one perhaps containing two hundred shot and the next a hundred and thirty. It is more difficult to get a round pattern too with a cylinder gun, since very frequently they string the shot up and down or in some other direction. Every barrel needs to be tested carefully whether it is choked or cylinder for some develop one fault and others another. Not infrequently a tube may place the bulk of its shot high, leaving the lower half of the circle thinly covered or the reverse. I have seen some guns fill up one corner densely with load after load to the detriment of the remainder of the target.

Guns may pattern better with one size of shot or load of powder than another, so it is well to experiment with the arm until its strong points and idiosyncrasies are fully understood.

Guns may have any degree of choke from full to a plain cylinder, but for purposes of comparison and illustration we will adopt the factory terms of full choke, or 70 per cent., half choke or 60 per cent., quarter choke or 50 per cent., improved cylinder or 40 per cent., plain cylinder or 30 per cent. The illustration shows the size of circle in which these various degrees of choke throw their patterns. For practical purposes barrels should be given a degree of choke dependent first upon the use for which they are intended, second the skill of the user, and third the gauge.

In calculating the degree of choke you would place in your gun barrels, do away with all preconceived notions as to the close shooting of small bores, for every gun of whatever gauge shoots into precisely the same size of circle if given a like amount of choke. Every full choked gun from an eight to a twenty-eight will pattern with its 70 per cent. into circle 1, or the thirty inch, half chokes into circle 2, quarter into 3, and so on. This has been proved beyond any possibility of question and every manufacturer will confirm it.

The use you would make of your gun should be governed by its power, and power is directly dependent upon pattern or the number of shot that can regularly be placed in the game. Of course this statement might be modified by the velocity of the charge, but in standard loads velocities of all gauges are so nearly equal that at present we can leave velocity out of the question and consider power as a simple matter of pattern and size of shot.

Certain kinds of work, either at the traps or in the field, necessitate a given amount of power, and power is pattern. All guns, whatever their gauge, that pattern 300 are of like power, other things being equal. This 300 target is considered the minimum for a reliable weapon to be used at the trap or on wildfowl, and it can only be secured in twelve and larger bores. It follows that as now bored no gun smaller than a twelve is quite powerful enough for trap and duck shooting. However, a sixteen will target 280 shot with its ordinary charge of an ounce or with an ounce and a sixteenth will reach the required 300, and we therefore find it fairly deadly on wildfowl.

Guns smaller than sixteen should be confined to the uplands. This 300 pattern will cut up quail considerably or any game that is shot at distances below thirty yards, and is therefore rather a special purpose than a general service arm.

For an all-round gun, a weapon excellent on wildfowl and the trap and unexcelled elsewhere, I should incline to favor a pattern of from 250 to 275 shot. This can be secured from a half choked twelve or a full choked sixteen. A target of 245 shot is obtainable from the twenty bore and therefore it will do on a pinch should the owner be confined to the one gun. Nevertheless a man will find himself handicapped considerably who is obliged to shoot ducks or face the traps with a light twenty bore.

Patterns of from 225 to 250 are strictly for the uplands where they will safely account for every species of game up to thirty-five yards or more. Twelve gauges 50 per cent, or quarter chokes, will afford this target and half choked sixteens or full choked twenties. Either of these arms, bored as given, are perfectly capable of accomplishing everything required of an upland gun.

A pattern of 200 shot is about as light as a sportsman can use without undue cruelty through crippling game. It is only adapted to the uplands and will be found much more deadly on quail and partridge than on other birds. It is not a safe load beyond thirty to thirty-three yards. This target can be obtained from an improved cylinder twelve, a quarter choked sixteen, a half choked twenty, and a full choked twenty-eight, any one of which is a very good quail gun, though requiring different degrees of skill to handle them effectively.

Short range guns, or those with patterns of less than 200 shot, have been used on quail and are very effective in the brush, but there is a constant temptation to use them at ranges longer than the pattern warrants, as a consequence pricking and wounding a great many birds that go away to die.

Keeping in mind that even for the uplands the lowest permissible pattern is 200, it will be apparent that really small bore like the twenty and the twenty-eight should never be modified below a half choke which would cover thirty-six inches at forty yards. If you are unable to place a circle of shot of this diameter on your game be content to shoot a larger bore that will permit a further modifying without sacrificing deadliness to an unsportsmanlike extent.

It is hardly necessary to mention here a proceeding that would naturally be followed by most men, that of using one pattern or degree of choke for the right barrel and a closer one for the left. In a twelve gauge a half choke for the first barrel and full for the second makes a more killing duck gun in the hands of any one but an expert than to have both barrels full choked. I have observed also that a pattern of 225 for the first barrel and 275 for the second is about the right thing for the average man in the uplands. The principle of different degrees of choke for either barrel applies to all gauges except the trap gun and the twenty-eight, both of which should be used in full choke only.

Here are some patterns of ten, twelve, sixteen, twenty, and twenty-eight gauge with standard loads in numbers eight, seven and one-half, seven, and six shot, full choke, half choke, quarter choke, improved cylinder, and plain cylinder.

FULL CHOKE (70 PER CENT. OF CHARGE)

gauge ounces shot pattern
10 1¼ 8 350.
12 1⅛ 8 315.
16 1 8 280.
20 ⅞ 8 245.
28 ¾ 8 210.

10 1¼ 7½ 301.
12 1⅛ 7½ 271.
16 1 7½ 241.
20 ⅞ 7½ 211.
28 ¾ 7½ 181.

10 1¼ 7 254.
12 1⅛ 7 228.
16 1 7 196.
20 ⅞ 7 178.
28 ¾ 7 153.

10 1¼ 6 190.
12 1⅛ 6 171.
16 1 6 152.
20 ⅞ 6 133.
28 ¾ 6 114.

HALF CHOKE (60 PER CENT. OF CHARGE)

gauge ounces shot pattern
10 1¼ 8 300.
12 1⅛ 8 270.
16 1 8 240.
20 ⅞ 8 210.
28 ¾ 8 180.

10 1¼ 7½ 260.
12 1⅛ 7½ 233.
16 1 7½ 207.
20 ⅞ 7½ 181.
28 ¾ 7½ 155.

10 1¼ 7 217.
12 1⅛ 7 196.
16 1 7 174.
20 ⅞ 7 152.
28 ¾ 7 130.

10 1¼ 6 163.
12 1⅛ 6 147.
16 1 6 130.
20 ⅞ 6 114.
28 ¾ 6 98.

QUARTER CHOKE (50 PER CENT. OF CHARGE)

gauge ounces shot pattern
10 1¼ 8 250.
12 1⅛ 8 225.
16 1 8 200.
20 ⅞ 8 175.
28 ¾ 8 150.

10 1¼ 7½ 216.
12 1⅛ 7½ 194.
16 1 7½ 172.
20 ⅞ 7½ 150.
28 ¾ 7½ 128.

10 1¼ 7 181.
12 1⅛ 7 162.
16 1 7 145.
20 ⅞ 7 127.
28 ¾ 7 109.

10 1¼ 6 136.
12 1⅛ 6 122.
16 1 6 109.
20 ⅞ 6 95.
28 ¾ 6 81.

IMPROVED CYLINDER (40 PER CENT. OF CHARGE)

gauge ounces shot pattern
10 1¼ 8 200.
12 1⅛ 8 180.
16 1 8 160.
20 ⅞ 8 140.
28 ¾ 8 120.

10 1¼ 7½ 177.
12 1⅛ 7½ 154.
16 1 7½ 138.
20 ⅞ 7½ 120.
28 ¾ 7½ 102.

10 1¼ 7 145.
12 1⅛ 7 130.
16 1 7 116.
20 ⅞ 7 102.
28 ¾ 7 87.

10 1¼ 6 108.
12 1⅛ 6 98.
16 1 6 87.
20 ⅞ 6 76.
28 ¾ 6 65.

PLAIN CYLINDER (30 PER CENT. OF CHARGE)

gauge ounces shot pattern
10 1¼ 8 150.
12 1⅛ 8 135.
16 1 8 120.
20 ⅞ 8 105.
28 ¾ 8 90.

10 1¼ 7½ 129.
12 1⅛ 7½ 116.
16 1 7½ 103.
20 ⅞ 7½ 90.
28 ¾ 7½ 77.

10 1¼ 7 108.
12 1⅛ 7 98.
16 1 7 87.
20 ⅞ 7 76.
28 ¾ 7 65.

10 1¼ 6 81.
12 1⅛ 6 73.
16 1 6 65.
20 ⅞ 6 57.
28 ¾ 6 49.

Some deductions can readily be made from these patterns. The larger bores have the greatest power for either one of two reasons, in any size of shot they make the denser pattern or they will place as many shot of one size in the target, say seven and one-half, as the next narrower gauge will eights. Every time you open the pattern of your gun one degree you in effect reduce the power to that of the next gauge lower. Reduce the choke of a twelve to sixty per cent. and you have in range and power only a sixteen gauge; reduce it to a quarter choke and the range drops to that of a twenty; still further open the twelve to an improved cylinder and you have a weapon of like power and range with the twenty-eight.

Select the maximum range at which you have determined your gun must kill regularly--we will call it thirty-five yards--,a pattern of 225 to 250 will accomplish the work, and you can secure the required effectiveness from a twenty full choke, a sixteen half choke, or a twelve quarter choke. The principle should always be remembered that every time you widen the pattern you reduce the range. To make this plainer when you spread the pattern six inches, that is from a full choke to a half choke, you shorten the killing range three yards. Reckoning thus, a full choked twelve will be as effective at forty yards as a plain cylinder twelve will at twenty-five. Opening the pattern of a twenty to a straight cylinder will reduce its range from thirty-five to twenty yards, and no shotgun is a practical weapon that will not kill regularly with one barrel or the other up to at least thirty yards.

SHOT VELOCITIES

The average gunner is liable to consider the flight of a charge of shot from gun to game as instantaneous, like the negro’s “smoke wagon”, “when it starts it’s thar,” but science comes along with facts that are not to be denied. In standard loads number seven shot flies over a forty yard course at the rate of 850 feet a second, and during the time the pellets are on the way a speedy sprinter would move over four feet and be entirely out of danger. If the shot charge was in the shape of a great black ball we could watch it move up to and strike the target. At the two hundred yard butts the writer has often curiously observed the bullets in their flight to the target, noted their curve at a little past mid-range, and could tell within a few inches of where the lead would land--this was rendered possible by the burning lubricant on the missile which left behind a faint blue smoke.

The matter of speed of flight in birds will be treated later, but at present it is sufficient to say that some species of wildfowl get up a speed only six times slower than that of the shot charge. Keeping this in mind, we can better appreciate the necessity for the utmost practicable velocity of shot, not only for the reason that less allowance would have to be made for rapidly flying birds, but because penetration on game is directly dependent on velocity.

As has been hinted in a previous chapter, shot could be given a much higher velocity than is now the standard, and many progressive sportsmen are demanding such ammunition. Gunbuilders and cartridge firms are busily experimenting with a view to meeting this demand some time in the future. They are very reluctant to change the standard velocity of their cartridges, however, because they are now regulated scientifically to suit our present systems of shotgun boring. If shot charges are to be given a higher velocity, then gunbuilders must set the pace by inventing some new system of boring that will permit a high rate of progress of shot through their tubes without ruining the pattern.

The standard velocity of shotgun charges has been fixed at 1,050 feet over a twenty-yard course, and much experimenting has led the cartridge people to conclude that this is about the highest velocity consistent with even and regular patterns. To be sure, many guns will make a good target with a higher velocity charge, but others will not and the manufacturers are forced to remember the weakest link in the chain. Nevertheless higher velocity charges will come some time because they are possible, and since they would greatly simplify the problems of wing-shooting the demand for them will become insistent.

Manufacturers endeavor to give all their loads of whatever gauge and size of shot approximately the same initial velocity; when the shot charge is reduced they load a less amount of powder to correspond. Of course the large shot retain their speed for a longer time, the difference in speed of number ones and tens at forty yards being 175 feet. This does not mean that the larger shot would be a hundred and seventy-five feet in advance of the smaller, but the big pellets would be eighteen to twenty feet in advance, and when they might strike the game the small shot would pass behind. All of which emphasizes, not only the need of a high muzzle velocity, but also the use of a size of shot which will retain this velocity to the greatest extent up to the maximum range.

Taking sevens, or pigeon shot, as a basis for calculating velocities, we find that with a mean velocity of 1,050 feet over the first twenty yards of the course, this has fallen to 850 feet at forty yards, and 750 at fifty yards. Experiments have proved that it takes a velocity of 750 feet to kill live pigeons with seven shot and nearly as much for quail. We could therefore fix upon fifty yards as the limit of range for seven shot whatever the gauge or load, though of course they might occasionally kill at longer distances through luckily striking a vital part. Number eight shot could only retain this necessary 750 feet of killing velocity up to forty-five yards which could be fixed as the maximum range of eights. Smaller shot would be still more restricted down to thirty yards for number ten shot on quail. Duck shot, sixes and fives, should maintain a killing penetration up to sixty yards.

Naturally the larger the shot, the greater their execution even with like velocities, which would lead to the inference that relatively large shot should be used in all instances, and so they should except for the absolute necessity of maintaining a sufficient density of pattern. A rifle bullet is more deadly than any size of shot, yet is perfectly useless in wing-shooting, for in order to kill you must first hit. It is usually considered that three shot or more are essential to a kill, the chances being that one of them will reach a vital spot and produce instant death. Less than this number may mean a cripple, no matter what the size of shot or its velocity and hence we must not sacrifice pattern even to secure increased penetration.

As has been shown, the size of the shot has much to do with both its velocity over the range and killing power, but the maximum size of shot that can be used is limited by the gauge of our gun and the way it is bored. The futility of shooting large shot in small gauges, open-bored, is shown in the diagram where three-quarter ounce of four shot is driven at a velocity high enough to kill, but with only a remote possibility of striking the bird with enough pellets.

With all this we return to the original proposition of large shot, big bores, and heavy charges as being necessary to execution at long range. The prime factors of power are: pattern, velocity, and size of shot. We might reverse the order and say that the size of the shot which it will handle effectively limits the twelve bore to fifty yards, the sixteen to forty-five, the twenty to forty.

Progress in gunboring has now reached a standstill from the fact noted that patterns cannot be maintained with charges much in excess of the standard 1,050 feet over a twenty-yard range. If this difficulty can be overcome and shot given a speed several hundred feet higher than is at present possible, power will at once be greatly augmented, the sixteen becoming as effective as the present twelve and so on.

It is not believed that any permanent limit has been reached in the boring of shotguns, or that some system of boring will not finally be developed that will permit high velocities while still retaining and even improving patterns. The matter is in the hands of sportsmen who can stimulate ingenuity by making their wants known. As one manufacturer puts it, we do not make more powerful weapons because the present output is good enough and meets every demand. But that is neither progress nor history.