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Last Updated on 17.08.10
The stopping power of a caliber represents the capacity to “shoot” a wounded animal, even if temporary. Is not the same thing as killing game. The explanation is the following: if 2 calibers have the same trajectory in the animal, one with a great stopping power will kill down the animal, and the weaker one will let it run under the effect of the adrenalin. In both cases, the animal dies from a good hit, but in case of a great stopping effect, the animal stays down and doesn’t have to be chased. The more important becomes the stopping power, the more the animal has teeth, claws and desire of revenge. There is no need to discuss about the power of stopping by a blow in the head, but about the blows in the chest, or even the imperfect blows.
The blow in the head made by any caliber kills the animal, if it gets in the circumvolutions of the brain. So, in order to compare the stopping caliber, we must define it somehow from a mathematic point of view. There have been a lot of sizes and theories concerning the stopping power of including the one you are reading now, and all of them are imperfect. In the beginning it has been considered that the energy describes the power of stopping, but it doesn’t really fit the reality (tested by FBI), then the moment, which is closer to the truth, but is still imperfect because it doesn’t take into account the shape and energy of the projectiles. When I wasn't born yet, a general and a colonel have made some experiments on cows and dead bodies using different calibers, speeds etc. All the fires have been shot "surgically" after which the autopsy was done immediately in order to determine to pathological effect. In 1920, a man smarter than me, called Hatcher, has created a formula that mathematically describes the closest stopping effect. From my point of view I consider the study and Hatcher's mathematic formula to be the most trustworthy. For those interested in the formula, I can describe you the mathematic part, but taking into account the fact that you read this kind of things during your spare time, I attach the formula in the "annexes". The result of the formula is a number that represents the stopping power and is used for comparisons between calibers. For example, if 22 lr has the stopping power of 5 and 22 wmr has the stopping power 8, 22 lr is weaker by (8-3)/8=37.5% than 22 wmr.
When the formula was created, the guns used to leave smoke, and little was known about the effect of supersonic projectiles. Therefore I have found another author (Taylor) who has improved the formula and being a practitioner I have considered him worth of trust and have adopted his formula. The formula is still imperfect but still is the closest estimation of the stopping effect. The final formula combines the moment of projection (speed *mass), with the transversal section, shape and expansion of the projectile and the supersonic effect on the game (more precisely on the temporary cavity). Bursting of enthusiasm, I have searched on the internet about the charts of calibers, but to my amazement, I have noticed that the formula has been applied almost only to the gun. With the help of Excel and the improved formula, I have created the following chart for riffles and hunting guns. I don't understand why there hasn't been created a chart for riffles until now, but maybe there is a reason and someone will find it. Until then, you can find bellow the chart for usual riffles. For most of the calibers, I have considered two types of projectiles, the extremes, FMG and perfect expanded soft point. Between these, there are an infinite possibilities, data about controlled expansion and perfect expansion. From my point of view, the stopping effect is very important for all the distances we usually shoot I have created the chart for 0, 50 yards (45.7m), 100 yards (91.4 m), 500 yards (457 m). All the sizes, beside the stopping power, are measures in English units.
