ecale3 said:
Would the .50AE round be faster than the .357? And does that algorithm or whatever take body armor into account?
If it's a question... you must know that there's four
main factors that are responsible of a projectile capability to penetrate X surface... they are the diameter, the mass, the impacting velocity and the bullet nose shape and type.
The diameter :
For the example, let's take two standard projectiles having the same mass, shape and velocity but diferent diameters... the one with the smallest caliber will achieve the deeper penetration.
The impacting velocity :
Here the two testing projectiles share the same caliber, mass and shape with diferent velocities... the faster one has the better penetration.
The mass :
The two bullets has the same caliber, velocity and shape but diferent weights... the heavier one will retain more energy and velocity and thus will travel further through the penetrated surface.
The nose shape and bullet type :
This is a rather complicated subject and it must be discussed... let's assume that the testing projectiles are the same in all aspects, except in nose shape... here you can understand that a conical projectile is more penetrating than a flat one, if its pointed it will achieve more penetration than if it was rounded...
Fully jacketed bullets have better penetration than semi-jacketed soft-pointed ones, because the brass or copper which are the most commonly used metals in bullet jackets are less likely to flatten and deformate than the exposed lead core of a semi-jacketed bullet. There's also the hollow pointed bullets that mushroomises when hitting a semi-fluid (soft) surface like watter or flesh, these projectiles cause more severe wounds to unarmored target but have a relatively poor penetration when compared to the fully jacketed ones. Some bullets tend to yaw and defragmentate after traveling through a certain amount of flesh... the 5.56x45mm NATO cartridge is famous for this phenomenon and may cause more tissue disruption to fat persons than to slim persons in which it will overpenetrate and integraly exit before it starts to tumble, causing "minor" disruptions.
In addition there's many sort of armor piercing cartridges especialy designed to achieve deeper penetrations even at long ranges. Some of those are designed as anti-personal solutions for heavily armored infantry wearing up to level III body armors, they usualy have a hardened tip and/or core made of special metal alloys. There's also large armor piercing bullets which discard a sabot uppon hitting the target, those big calibers are used in anti-material riffles.
The previous exemples are just two sorts of AP cartridges among many others.
The Poncelet (must be a physician of the 19th century) algorithm is the simpliest way (but not the most accurate) to calculate the penetration of a given projectile by oposing the diameter, the mass and the velocity of the projectile to the pressure and density of the hitten surface, assuming that all projectiles are non-fragmenting and non-expanding flat-nosed perfect cylinders. This calculation although not realy accurate for practical purposes, can give us an overall view on projectile penetration and is perfect for comparing diferent types of calibers.
You may know also that there's not only one sort of bullet in every caliber. Two bullets of a same caliber and designed to be fired from the same weapon can widely differ in characteristics (projectile weight, tail and nose shape, material of construction, powder charge...) such variations are intended to affect both external and terminal ballistics.
Here is the ballistic datas of two diferent .357 Magnum catridges fired from the same 4" barrel to show the diference :
Caliber : .357 Magnum
Weight : 125 grains
Type : Jacketed Soft Point
Muzzle Velocity : 1450 Feet Per Second
Muzzle Energy : 583 ft-lbs
Caliber : .357 Magnum
Weight : 158 grs.
Type : Semi Jacketed Hollow Point
Muzzle Velocity : 1235 FPS
Muzzle Energy : 535 ft-lbs
The greater muzzle velocity a 125 grains .357 Magnum bullet can achieve is when fired from a longer barreled weapon like carabine and it is of about 1500 FPS.
The velocity of a standard JHP 311 grains .50AE bullet fired from a relatively short barrel is of 1400 FPS.
Softer .50AE bullets fired from longer barrels may achieve velocities up to 1580 FPS.
Finaly, for game purpose I suggest that the .50AE and .357 Magnum have the same velocity, the .50AE should be aproximatively 20% more penetrating than the .357 Magnum. Because the .50AE is heavier, it will retain more velocity over distance than the .357 Magnum and will thus travel further.
