When choosing, you have to look at the accuracy and deformation of the bullets used for both the smooth bore and the rifle.
Smooth-bore shotgun bullets, according to various brands, they are heavy from 29 to 32 g. of more or less hard lead and of different shapes, almost suitable ... even for choked barrels, and they have various tricks to be stabilized such as the fletching wad, the fins, which should give a rotational motion, and so on. They are animated by a speed ranging from 300 to 400 m / sec at the mouth. The best known boar are Gualandi, Brenneke, Winchester and Remington. When choosing, you have to look at the accuracy and deformation of the ball itself.
It differs, according to some evidence, the cartridge (bullet wad) Gualandi of 32 grams with an initial speed of 500 m / sec and a declared kinetic energy of 400 kgm: it is effective and precise even at 100 meters. It thus approaches the performance of the carbine, and also has a good deformation. On the other hand, the bullets of the rifles are not very heavy, animated by a strong speed ranging from 700 to 950 m / sec with a very tense trajectory compared to the rifle bullets. Without a telescope you can stop the running animal up to 100 meters, the further it is difficult for the target that is too small; with an appropriate telescope (such as the 1,5-6 × 40), taking into account the trajectory and the advance, even at 200 meters and beyond. The most used caliber is the 30-06 Springfield, designed for the American military rifle of the same name, which with bullets of 160-180 grains (one grain equals 0,064 grams) is animated by a muzzle velocity of 800-900 m! . It has a kinetic energy that reaches about 100 kgm at 350 m. There is a wide choice of bullets, and this common cartridge is well enough for animals weighing around 100 kilos. An excellent caliber derived from the 30-06 is the 35 Whelen, more rabid and powerful, chambered only in Remington rifles. 280 Rem can also be mentioned. or at least 270, but it is a bit scarce. Those who are more pessimistic can use the 300 Winchester Magnum, the 9,3 × 62 or even the 338 Winchester Magnum, certainly exuberant for our suids. Only hunters who want to do a bit of "ground", or have the opportunity to hunt the large specimens of central Europe of over 200 kilos, can choose these calibers. In my opinion in Italy the 30-06, the 35 Whelen, or at least the 300 Winchester Magnum can be used in the rifles. Express rifles today are also available at affordable prices, and are generally chambered with the very powerful rimmed 9,3 × 74 caliber or with other valid calibers such as the 8 × 57 Jrs derived from the German Mauser or the 7 × 65.
You can also choose express chambered with cartridges with heavier bullets, naturally animated by lower speeds such as the 444 Marlin or the old 45/70 Government, not suitable for long distances. I've seen some snobs shoot at boars and spoil them with the 375 .H & H Magnum or even with the 458 Winchester Magnum just to give it importance, far too exuberant for the black beast. Regarding the choice of the type of rifle bullet, I do not think a table is necessary as the performance, speed, accuracy and kinetic energy of the various brands, Rws, Federal, Norma, Winchester, Remington. and so on, they are similar or with few differences. Then only the type of ball has to be taken into account. The armored balls, almost non-deformable, pass from side to side the prey even if hit in the shoulder (naturally not meeting bones), thus having a very bad stopping power with the effect of yielding very little kinetic energy and not causing significant damage. The animal from internal bleeding can die far away and after much suffering. In the opposite case, if the bullet is very deformable and animated by an exuberant speed it can shatter on the surface without penetrating our leathery-skinned game, causing only superficial wounds. So the choice of the ball is important. In a first analysis of the bullets it can be said that there are three main types:
- fully armored full jacked or semiblindati
- soft toe soft points
- hollow point hollow points.
Lightly deformable fully armored projectiles are not suitable. Balls of at least 170 grains are needed, or with tricks in the coating which, upon impact, make them significantly increase in diameter, which deform in depth or even shatter in the upper part. The choice is varied, I can suggest the 180 grains soft point core locked Remington's, Norma's Vulcan, Rws' Tug's, Winchester's Silvertip or, better, Winchester's Balistic Tip. In the market there are also other types of suitable balls that have a good deformation.
It is important not to choose the pointed, hard lead armored ones that are only suitable for very long shots on soft game. One last tip: avoid the use of heavy bullets of 220 grains or more, not suitable for semi-automatic rifles that often fail to "scrap".