In the article "Army Pistol and Stopping Action of Pistol Cartridges" the concept of stopping action given by D. Towert was given:
In my opinion, the concept of "stopping action" and "lethal action" are inextricably linked. As long as the enemy is alive, there is always a risk that he will come to his senses and continue to actively resist. Only his complete and final death can guarantee the absence of resistance from the enemy.
Based on this: The stopping action is the time of inflicting death on an object from the moment a bullet hits it - the speed at which death occurs. The shorter the time between the hit of the bullet and the onset of death, the higher the stopping effect.
It would seem, based on the above definition, the stopping action of the ammunition could be characterized by a time characteristic - 1 second, two seconds, and so on. The problem is that it is difficult to determine the time of death for all potential targets with a 100% probability.
In this case, the probability of death can be considered as a quantitative assessment of the stopping action: The quantitative measure of stopping action is the probability of causing death to an object, from the moment a bullet hits it, through multiple intervals of time (presumably 1 second).
That is, the higher stopping effect of ammunition # 1 compared to ammunition # 2 means that ammunition # 1 leads to death within a certain period of time with a higher probability than ammunition # 2. The numerical size of this probability characterizes the stopping effect of the ammunition.
Technically, the characteristic "stopping action of the ammunition" can look like a ruler of the probabilities of causing death in the first second, second second, third second, etc. Accordingly, the higher the probability of the enemy's death in a shorter period of time, the higher the stopping effect.
How can you actually determine the likelihood of inflicting death on a target at a particular point in time? It is extremely difficult to determine the characteristics of the stopping action by calculation, there are too many unforeseen factors determined by the various mechanisms of the bullet's impact on the target, although it is certainly necessary to develop a methodology for such a calculation.
But nevertheless, most likely, it will be necessary to create some chest targets from a ballistic gel, including a conditional "skeleton" and "nervous system" from a network of conductors. When a bullet hits the target, it will break the conductors, which will track the movement of the bullet in the target in real time.
The indications of the conductors should be superimposed on a virtual model, which should reflect the location of internal organs, simulate conditional bleeding in case of damage to blood vessels, organs, etc., and based on this, the estimated time of death is determined, taking into account the existing medical experience in the field of bullet wounds …
The target, of course, will be disposable. It is quite possible that in order to reduce the cost, such targets will be printed on a 3D printer. It may seem to someone that this is difficult and expensive, but I see no other way to get information about the effectiveness of new and existing ammunition. In the end, it is possible to proceed to tests on such targets only after other types of tests - for accuracy, armor penetration, penetration into a ballistic gel, etc.
Ammunition parameters providing stopping action
So what parameters of the ammunition provide a stopping effect on the target, in accordance with the above definitions?
In fact, there are only two such parameters:
1. Damage caused directly by the body of the bullet.
2. Damage caused by secondary damaging factors: hydrodynamic shock, temporary pulsating cavity, bone fragments, etc.
According to the results of FBI research from 1986, which was mentioned in the article "Army pistol and the stopping effect of pistol cartridges", only direct hitting the target with a bullet can guarantee the target is disabled:
The secondary factors indicated in clause 2, although desirable, are extremely poorly predictable in their action. In other words, if a temporary pulsating cavity appears upon impact of a bullet, then this is good, but it is inappropriate to develop an ammunition, proceeding precisely from the need to create a temporary pulsating cavity by it.
Thus, the main damaging factor is mechanical damage caused directly by the body of the bullet
The mechanical damage caused by the bullet can be increased due to the expansion of the expansive bullet, with a corresponding increase in its diameter, or due to the controlled fragmentation of the bullet into separate elements, which significantly increases the likelihood of damage to vital organs.
The problem is that expansive and fragmented solutions perform much worse on goals behind the obstacle, and do not always show a consistently repeatable result. Depending on the situation, the expansive bullet may not open, and the fragmented bullet may not split into submunitions, which makes the result of their use unpredictable. This is indirectly stated in the previously mentioned 1986 FBI report on the stopping effect of ammunition:
Nevertheless, with the adoption of the SIG Sauer P320 M17 pistol, the United States apparently decided to cease to comply with the provisions of the Hague Convention of 1899 (which, however, they did not sign) by adopting the M1152 and M1153 cartridges, the latter of which is expansive (JHP) …
It is stated that the M1152 FMJ one-piece cartridge is designed to defeat enemy soldiers, and the M1153 (JHP) expansive cartridge is necessary in situations where limited bullet penetration is necessary to reduce collateral damage.
However, for the new Russian pistol "Boa" there is also an SP-12 cartridge with an expansive bullet. Of course, it is possible that it will be used only by the fighters of the Russian Guard and the Ministry of Internal Affairs, but apparently some provisions of the Hague Convention of 1899 will soon go to the dustbin of history after the anti-missile defense treaty, the treaty on intermediate and shorter-range missiles, and others.
Another argument against expansive and fragmented bullets is a reduction in their penetration depth due to the energy expenditure for opening / fragmentation and an increase in the cross-section of the bullet / bullet fragments.
The depth of penetration of a bullet is one of the critical indicators characterizing the damaging properties of an ammunition
It is this factor that does not always allow such ammunition as 5, 45x18 MPTs to provide a high probability of hitting targets. In some cases, the initial energy of the bullet may simply not be enough to penetrate the body to the depth necessary to damage vital organs.
What is the optimal penetration depth? The FBI Commission claims that it is about 25 centimeters. However, there are certain nuances regarding the depth of penetration. Consider three options:
1. The bullet entered the body, but did not penetrate deep enough to damage the vital internal organs.
2. The bullet entered the body deep enough and stopped in the body.
3. The bullet went right through.
What is the best option? We discard option number 1 at once, everything is clear with it. But with options # 2 and # 3, it's not so simple. It is believed that the bullet must remain in the body, completely transferring its energy to the body. The question is, what does it mean to “transfer energy” from a practical point of view? Energy can be transferred in different ways, what will the bullet spend its energy on, is it not for heating the body?
No, she will spend it on the mechanical destruction of body tissues, in the presence of NIB for their destruction, as well as on the deformation of the bullet itself in the process of moving in the body and overcoming the NIB. By the way, one of the tasks solved in the design of armor-piercing bullets of 9 mm caliber is the choice of such a form of the bullet core jacket, which would reduce the bullet speed to a minimum during separation, when the NIB penetrates, but one way or another, part of the energy is spent on this.
Consider two options: one bullet entered the body with an energy of 1000 J and left the body (through penetration) with an energy of 400 J, and the second entered the body with an energy of 500 J and remained in it. Which one will do more damage, which one has a higher stopping effect? Formally, the first gave more energy. But then what about the fact that a bullet stuck in the body is more lethal, and, according to the general opinion, the stopping effect is higher precisely in the case when the bullet remains in the body?
It is possible that this is more connected not with the fact of energy transfer, but with the fact that the bullet, while remaining in the body, continues to exert pressure on the internal tissues, causing additional injuries, increasing bleeding, especially when the body moves
Ways to increase the stopping effect (speed of death)
What methods can be implemented to increase the transfer of bullet energy to tissue destruction and bullet retention in tissues? First of all, this is a change in the shape of the bullet, for example, the implementation of bullets with a flat rather than an ogival tip, as is done in the aforementioned 9x19 mm M1152 cartridge for the US armed forces. The flat head of the bullet also reduces the likelihood of ricochet.
If we return to the conversation about the transition from the 7.62x25 mm cartridge to the 9x18 mm cartridge, then the use of a flat head part of the bullet could well solve the problem of the through-penetration of the body by the bullet of the 7.62x25 mm cartridge. Moreover, a higher initial bullet energy of cartridge 7, 62x25 mm TT would provide a greater depth of penetration with a corresponding increase in the likelihood of damage to vital organs.
Another option is bullets with low resistance, which, when they hit the body, begin to tumble, which significantly increases the damage done.
Does size matter?
In the context of the fact that the main damaging factor is the mechanical destruction of organs by the body of the bullet, how big will the increase in caliber have? Of course, a bullet with a diameter of 11 mm will form a larger wound channel than a bullet with a diameter of 5 mm, unless of course we consider the option of an unstable bullet, but how much more stopping effect (read the rate of death) this will give in quantitative terms can only be determined by test results, it is assumed the method of which is described above.
Based on the analysis of ammunition used for hunting, it can be assumed that the priority factors providing a high stopping effect are the initial energy, shape and composition of the bullet material. The caliber of the ammunition in this case is a secondary factor, which is determined based on the required energy, the shape and material of the bullet, as well as the requirements of external and internal ballistics.
With regard to army weapons, in which firing in bursts or short bursts can be realized, it is necessary to choose the minimum caliber that allows the requirements of the previous paragraph to be met. At the same time, the stopping effect of the weapon-cartridge complex is increased by hitting the target simultaneously with several ammunition, as was discussed in the article "A promising army pistol based on the PDW concept."
This is again indirectly stated in the FBI report from 1986:
Speaking about comparing the stopping effect of 11 mm and 5 mm diameter bullets with equal energy, it is necessary to take into account a significant reduction in ammunition for larger caliber ammunition. Therefore, it is quite justified to compare the stopping effect of one bullet with a diameter of 11 mm and two bullets with a diameter of 5 mm. At the same time, in order to ensure the same penetration depth, the energy of a bullet with a diameter of 11 mm must be higher than that of two bullets with a diameter of 5 mm, which in turn significantly complicates firing from such a weapon. The need to defeat targets protected by the NIB is also an argument in favor of small-caliber weapons.
If we are talking about a "promising army pistol based on the PDW concept", then firing in short bursts of two shots allows us to implement the option of combined use of ammunition, with a different type of destructive action. For example, when one bullet is made in a variant with high armor penetration, as in cartridges 5, 45x39 mm, 5, 56x45 mm, 5, 7x28 mm, and the second bullet is made with a flat head. At the same time, they are loaded into the store one by one, and in the main mode of firing in short bursts of two rounds, the positive qualities of both versions of the bullets are summed up.
Thus, when firing at a target protected by the NIB, a bullet with a flat head part carries out a beyond-barrier effect on the target (if possible) without penetration, while the NIB elements may be damaged, and the second bullet, with increased armor penetration, penetrates the NIB and beyond the barriers to hitting the target. When firing at a target unprotected by the NIB, a bullet with a flat head penetrates the body to a sufficient depth, and remains there, maximally injuring the internal organs, and the second bullet, with increased armor penetration, strikes the target with an effect characteristic of bullets with low resistance, when it is assumed that in some cases it can carry out a through penetration of the target.
However, the assumption of the possible need to use a combined version, with firing two types of bullets simultaneously, can be refuted by the test results, which will show that the simultaneous use of two bullets with increased armor penetration and low resistance will show comparable or higher efficiency.
In this case, is there any sense at all in pistol cartridges of 9-11 mm caliber, if you do not take into account the established stereotypes? Yes, if we are talking about civilian or police weapons, in which firing in bursts is prohibited and it is necessary to limit the range of the bullet, to prevent accidental damage to unauthorized persons. This is especially true for civilian weapons, in which artificial restrictions on the capacity of the magazine can be established, for example, up to ten rounds. Given that both the police and civilians are significantly less likely to meet with the enemy protected by the NIB, the role of expansive and fragmented bullets increases if they are allowed for use by the legislation of a particular country.
But for a promising army pistol, in which it is necessary to provide both a high stopping effect (the speed of death) and the defeat of targets protected by the NIB, the best solution is the use of small-caliber ammunition in combination with firing short bursts of two shots.
