Hunting Ballistics: Slug balls and shooting boar
Hunting Ballistics: Slug balls and shooting Various inventions: 1) Spherical - 2) Lethal - 3) Destructor - 4) Ruled ball - 5) Ball with concentrator - 6) Berntheisel-Luneville in fragments 7) In fragments - 8) Lavré in chained fragments - 9) Treff di Mahrhold and Peterlongo - 10) Oberhammer - 11) Steel-pointed - 12) Kohler - 13) Hollow ball MF (From Lampel-Mahrhold's Waffenlexikon).
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From the letters of those who ask me for ballistic advice I have seen how there is very little clarity of ideas on the use of single balls (in English slug). Most fail to understand why these balls are so accurate in vendors' test targets and instead miss the target on the court.
A bullet to be accurate must be stabilized. In rifles with rifles, stabilization is obtained by giving the elongated bullet, even up to 5 calibers, a rapid rotational movement. In smooth-bore shotguns it is not possible to give the projectile a sufficient rotation and one must resort to the other system consisting in the fletching of the projectile by lightening the rear part with a cavity at the base or by fixing a wad to the base of the projectile, so that (in both cases) the center of gravity is shifted forward. Stabilizer fins can also be added; these involve a slight loss of accuracy, but allow the use of much longer projectiles (and therefore with greater sectional density, such as arrows and missiles), which retain stability even in very curved trajectories and do not require to be fired in rifled barrels.
The problem of building bullets for shotguns with precision and harm has haunted hundreds of inventors who in the last century have patented an incredible number of inventions, more or less imaginative. In the end, however, it was seen that we cannot deviate from the solution seen above and at the moment the most reliable balls are those that combine a lead ball with a wad (sometimes shaped to increase the fletching effect), as happens in the ball. Brenneke and Gualandi in the ball. The Blondeau ball, French, looks a bit like a big diabolo.
The only real innovation in the field of slugs is represented by the ball fitted with a fletching with fins invented in 1983 by the French ing. Sauvestre (also designer of the anti-tank arrow bullet used in the French army) which uses a sub-calibrated bullet, equipped with a plastic sabot that detaches a short distance from the muzzle of the weapon.
Sauvestre ball. The weight is 26 g and the initial speed of 580 ms.
The bullet, very elongated and with a hollow point, has a diameter of only 11,4 mm and is formed by a hard core coated with lead; the bullet body has showy annular grooves. It is fired with an initial velocity of about 500 ms (580 ms in the 12 magnum using the same 26 gram bullet) and at 100 meters it still has a velocity of 375 ms (430 for the magnum) with an energy of 1850 J ( 2440 J for the magnum). At this distance, a cross wind of 10 ms (i.e. a strong breeze that moves bushes and trees) moves a normal slug bullet of 75 cm, the Sauvestre bullet of 30 cm, a rifle bullet of about ten centimeters.
Trajectory of the Sauvestre ball with the fall of the bullet at
various distances; the manufacturer indicates an optimal reset at 107 meters,
which allows you to shoot up to 120 meters
with a deviation from the trajectory of +/- 5 cm.
All these bullets, weighing from 24 to 39 grams and starting speed of 450-580 ms, tested with support and scope, provide very respectable shot patterns of less than 5 cm in diameter at 50 meters distance. The reason why hunters, on the other hand, have the impression of poor accuracy is twofold and it is easy to say.
In the first place, shotguns are not suitable for this type of balls. The guns designed to shoot shot are zeroed for a shot at 35 meters and the two barrels are coupled so that their respective shot patterns overlap at this distance; the reeds are, so to speak, cross-eyed, and converge on an ideal point at 35 meters. Shooting fifty meters away, it happens that the ball fired with the right barrel hits several centimeters to the left of the aimed point and the left one several centimeters to the right, with a total difference that makes the grouping appear disastrous. So the problem is not that the ball is not accurate, but that the shotgun does not shoot at the targeted point. Obviously, if the target is at a greater distance, the defect worsens proportionally.
This defect does not occur for over-and-under shotguns and single-barreled shotguns, but almost always the second defect takes over, that of zeroing, which causes firing much higher (up to 35 meters) or lower (over 40 meters). ) of the targeted point. Shotguns are zeroed for a distance of 35 meters so that the center of the shot pattern is 10-15cm above the target point, which is not adequate for a bullet that falls only about 5cm at that distance. In order to have a trajectory that does not deviate from the line of sight more than 4 cm (above or below), the firearm should be zeroed, using Brenneke or Gualandi bullets, at a distance of 70 meters and, using Sauvestre bullets, at the distance of 100 meters.
Let's see a practical example with a Gualandi or Brenneke type ball weighing 28 g and an initial speed of 500 ms., Bearing in mind that the initial speed values indicated by the manufacturers are always indicative because the actual speed then varies depending on the loading of the cartridge and barrel length.
With zeroing at 70 meters the trajectory of the bullet will be above the line of sight of 3 cm at 50 meters, at 90 meters it will be below it by about ten cm, more than acceptable for such a distance, without scope.
If, on the other hand, the weapon had been zeroed at 35 meters, the bullet at 75 meters would have already been about ten centimeters lower than the targeted point which, at 100 meters, would have become about twenty.
The lighter and more aerodynamic Sauvestre bullet, with an initial speed of 580 ms, can be zeroed at 107 meters so that at 120 meters the distance from the line of sight is only 5 cm. If it is fired with the weapon reset at 35 meters, the range at 100 meters is about 10 cm and at 75 m about 5 cm.
The conclusion is therefore that with an over / under shotgun or semi-automatic shotgun, that not has been properly zeroed, slugs can be fired with sufficient accuracy as long as the target is no more than 60 meters; which means that these weapons are fine in the vast majority of situations that arise in driven hunts. The situation does not change if instead of bullets weighing less than 30 g, magnum cartridges are fired with a ball of about 40 g. Initial energy is gained, but the trajectory is more or less the same.
All the tests carried out agree that the Brenneke, Gualandi and Blondeau balls are almost equivalent; the Solengo bullets and those with sabot from Federal and Winchester were much less accurate (at 50 meters, the 8-10 cm range, compared to the 4-5 cm of the previous ones). From this it follows that in the smooth-bore shotgun the sabot is counterproductive, except in the case of the Sauvestre with arrow fletching.
Gualandi balls with plastic wad fixed to the ball.
The ball weighs 28,25 grams (12/70 cal.) And the initial speed is around 500 ms.
There are also rifles cal. 12 with rifled barrel, specially designed to shoot slug balls. No doubt they are properly zeroed but, when a rifled barrel is used, the question arises whether it makes sense to use bullets that have adopted folds in order to be fired in smooth barrels, with all the consequent defects. If the barrel is rifled, it means that it is able to stabilize a bullet by virtue of the rotational movement impressed on it and therefore an ogival-shaped bullet should be used, capable of giving the best from the aerodynamic profile; the trouble is that an elongated 12-gauge lead bullet would have an excessive weight (even the simple spherical ball reaches 37 grams!), impossible for pressure, slowness and recoil; if you try to solve the problem by lightening the bullet, you have an increase in the initial speed incompatible with the use of bare lead which would not withstand the stress of the lines. It would therefore be necessary to design a special under-calibrated ball which, for what has been said, could only be an elongated ball, with a sabot resistant to scratching. The advantage obtainable with such a ball would not be exceptional, but still useful: the weapon could be zeroed on 100 meters, and the optimal aerodynamic shape would allow you to have good energy even at such a distance.
As far as I know, at the moment the rifled barrels available are:
- the ball Golden slug of the Brenneke which, however, is only a makeshift: it is in bare lead, albeit gilded, it has a front profile that is very little aerodynamic and therefore cannot exploit the advantages of the rifled barrel.
Pat Remington Copper Solid
- The Remington Copper Solid bullet in copper alloy with sabot which however is not the most suitable for shooting in smooth barrels and does not offer any aerodynamic advantages.
Neither of them is therefore able to offer substantial advantages over their use in smoothbore.
- A very recent production by Brenneke seems to offer something new; is the under-calibrated Super Sabot bullet (16mm). The 31,8g brass sabot bullet should expand up to 25mm and, when fired with a rifled barrel, should have a 60mm shot pattern. at 100 meters. It is very expensive (4 Euro each cartridge). See the appendix with the image at the end
The Sauvesttre bullet, as already mentioned, has an arrow fletching and must not be fired into a rifled barrel which gives it a harmful rotational effect.
Many hunters are beset by doubts as to whether the dry ball has sufficient stopping power.
If you consider that the shotgun for hunting wild boar or other aggressive animals, is chosen for its ease of handling because when you need to shoot in the woods or with quick reflexes, it allows you to shoot the wild almost "on the fly", which impracticable with a rifled rifle (if only because there is no training to hold it for an instinctive shot) it is clear that you can also give up some stopping power which, however, is more than enough. A dry ball loses about a quarter of its speed in 50 meters of flight; therefore the 39 gr ball, with an initial speed of 460 ms, at 50 meters has an energy of about 2300 Joules; the ball of about 30 grams at 50 meters retains a speed of about 340 ms and therefore an energy of about 1700 J. At normal hunting distances, with projectiles designed to allow maximum energy transfer to the wild, it is therefore within the of energy and speed which, according to studies carried out, allow you to fatally injure an animal weighing 50 kg. At 100 meters the speed is reduced to about six tenths of the initial one and the values indicated above would become, respectively, about 1500 and 1100 J, well below the values obtainable with a rifle, unless the Sauvestre bullet is used which, in the 12 magnum caliber, is comparable to 7 × 64 or 8 × 57, having an energy of 3250 J at 50 meters and 2440 J at 100 m ..
It is hardly necessary to point out that, in terms of penetration and injury, the bullet that has the greatest sectional density is preferable and the one that has the greatest speed on impact.
From this it also appears that it is nonsense to mount a telescope on a shotgun for dry balls: if you want to shoot quickly and up to 100 meters (distance that the bullet covers in a time of about a third of a second, which is why it can happen having to shoot two or three meters ahead of the running wild boar), the telescope is only annoying; if you want to shoot over a hundred meters, aiming calmly, it is preferable to use a rifle.
The conclusions of the above could be the following:
- if you shoot with your arms at normal hunting distances, within about fifty meters, the various types of bullets are equivalent, on a practical level, in terms of energy and precision. The Sauvestre ball stands out for its sectional density and energy;
- if you intend to shoot at greater distances, up to one hundred meters, the weapon must be reset appropriately (which is not possible for the weapons now in use) or it is necessary to get used to instinctively calculating that the bullet will hit up to fifteen centimeters more down;
- rifles with rifles do not give significant advantages, except that of a better zeroing, because there are still no satisfactory bullets designed specifically for them; the real advantage is the… legal one, because for 12-gauge semi-automatic rifles with rifled barrel there is no limit of shots (except for special provisions contained in the hunting calendar). However, there is the disadvantage of not being able to use shot cartridges, given the worsening of the pattern.
Those who use slug bullets often wonder if they can cause damage to a shotgun with choked barrels. Doubts do not have much reason to exist because all lead bullets on the market have been designed to be fired even from choked barrels and therefore, unless otherwise indicated that the manufacturer is required to indicate on the package, there are no reasons not to use them. Undoubtedly, however, it is necessary not to exaggerate because the slug cartridges cause abnormal stresses to the barrels due to the fact that the point of maximum pressure in the barrel moves about ten centimeters forward, where in normal rifles the barrel wall is already thinned, and for the the fact that the ball is forced into the choke. We must therefore avoid firing these ammunition into old rifles whose resistance we are not sure of.
In the use of dry balls it should be remembered that they are easily destabilized and deflected by small twigs and that they easily bounce off the ground or trees, remaining dangerous up to almost a kilometer away. Average energy values of the various balls:
|
50 m |
100 m |
||
|
|
Brenneke, Gualandi, etc. 30 gr. approximately |
1500 J |
1100 J |
|
|
Brenneke, Gualandi, etc. 40 gr. approximately |
2000 J |
1500 J |
|
|
Normal Sauvestre |
2500 J |
1850 J |
|
|
Sauvestre magnum |
3220 J |
2450 J |
Now some brief notes on wild boar shooting.
Il boar it is a wild that, for various reasons of its own safety and that of the dogs, it is better to kill on the spot rather than to injure. It is also particularly resistant and resistant to pain; therefore we need suitable gauges.
The wild boar has a weight ranging from 60 to 300 kg, even if such large animals are still found only in Eastern Europe; with us they are around the minimum values, but it is necessary to foresee the possibility of meeting animals between 100-150 kg.
The shooting distance is always limited and it is difficult to exceed 50 meters.
The minimum energy required is calculated in 2000 joules, which is achieved by a good slug bullet or rifled rifle bullet of at least 7mm. Those who go to Romania to shoot wild boars weighing over 200 kg can usefully reach up to a caliber of 9 mm.
In the Swiss canton of Jura, the use of buckshot of at least 7 mm in diameter (two grams in weight) is also permitted.
In Belgium, Royal St-Hubert recommends the slug shotgun.
Therefore, a ball is not needed for long ranges and with a straight shot, but a ball that causes a strong shock effect.
The accuracy of the weapon is secondary because in the wild boar hunting a quick shot is required which does not give the time for an accurate aim: the ideal is a weapon of quick bracing, with a good line of sight, to be used with standard loads and bullets which are calculated to give an acceptable recoil.
In Italy, absurd fashions have recently been developing, such as the use of rifles that use short weapon ammunition. They are totally inadequate ammunition with energy between 1000-1500 Joules, unless you resort to exaggerated charges that are hardly justifiable.
Appendix
I add some data taken from the Visier magazine, May 2002.
Here is an image that represents the most popular balls in Europe
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In order: Aguilla Practical - Brenneke RubinSabot - Brenneke SuperSabot - Brenneke KO - Cooppal Stream - Diana Akah - Federal Premium Sabot Slug - Federal Classic Slug - Geco Competition Slug with Brenneke KO ball
Among the novelties, the Brenneke RubinSabot cartridge with a plastic fletching ball more or less reminiscent of the Brenneke KO The ball weighs 28 gr. and has an initial speed of 510 ms (J. 3641) which drops to 410 ms at 50 meters (J. 2285) and to 334 ms at 100 meters (J. 1562).
More innovative is the SuperSabot bullet which has its limit in the fact that, having no fletching, it must be fired from rifled barrels in order to be stabilized. The ball weighs 31,8 g and the speed and energy values are 465 ms (J. 3438) at the mouth, 374 ms (J. 2220) at 50 m. and 317 ms (J. 1598) at 100 meters. The ball has a diameter of 16 mm. and it is on the outside of a brass alloy with a composite core, as seen in the image below; the outer part deforms into a mushroom on impact with a notable and rapid transfer of energy.
The 5-shot grouping at 100 meters was less than 7 cm in diameter.
