MTMilitiaman
Member
The effective point target range of the M16A4 service rifle with M855 is listed as 550 yards, IIRC. This number is derived from the round's ability to penetrate a standard 1980s-issue Soviet helmet and the computed hit percentages of average infantrymen. In the past, the military has used 1/2" pine boards. This all results in numbers that are abstract and ambiguous, difficult to apply in the real world and often laughably optimistic. A 5.56mm rifle round is certainly capable of poking a potentially lethal hole in someone from 550 yards away, but this distance is much farther than our experience with the round tells us it is truly effective. A term that is relative to a politician or officer in the rear might be less debatable for the US Marine engaging across ridge lines in Afghanistan. Simply put, it is not really "effective" in the sense that we need it to be, if they are still shooting at you. Or, for the sportsman, if you still have to track the animal. We need to revise how we express the effectiveness of our weapons so that it actually applies to how we use them.
Our knowledge of terminal ballistics has shown us the importance of velocity in wounding. We now know that energy as a figure for determining potential trauma is limited. For those with even an superficial understanding of basic physics concepts, the impulse matters as much as the amount of energy. The impulse is the amount of time it takes energy to be transferred. A projectile has energy as mass and velocity. The only way it uses this energy is through losing mass or velocity. The amount of time this takes is crucial in determining how your projectile interacts with living tissue, and is a function of velocity.
We all know what "hydrostatic shock" is, or are at least aware of it as a concept. The pressurized shock wave that moves away from the impact of a projectile in a liquid or semi-liquid medium can be demonstrated to awesome effect simply by shooting milk jugs filled with water. This effect is present regardless of the velocity of the projectile. However, our tissue is thankfully much more resilient to these forces than plastic milk jugs. Living tissue stretches and deforms, then returns to normal with little to no permanent damage. This allows the body to absorb an incredible amount of energy without damage because the impulse is too long. For this reason, energy is irrelevant as a indicator of effectiveness with projectile impacts under 2200 fps. At velocities above 2200 fps, the impulse is too short, the impact too violent. Tissue can not stretch or deform far or fast enough. It tears and breaks apart, damaging or destroying tissue for several inches beyond the path of the actual projectile. This is what makes a rifle a rifle and a handgun a handgun. Speed kills. Whereas about 1 in 4 people shot in the torso with a handgun dies, about 1 in 4 people shot in the torso with a rifle lives. Hollywood lied to you. High velocity rifles are orders of magnitude more effective than handguns.
So our first indicator of effectiveness should be the range to which our weapon will be truly effective, bring shock and awe, and "kill like a rifle." For this, we want 1000 foot pounds of energy on target and the velocity to use it, so at least 2200 fps. All of this power does no good if the average shooter can't find his mark, so our definition of effective range should include the ability to realistically find, range, and engage with a high degree of accuracy. So for the purposes of this discussion, we are going to say that:
Effective Point Target Rifle Range of a given firearm/optic/load is that which the individual marksman can identify, range, and engage with a hit percentage of no less than 75% and deliver 1000 foot pounds on target with at least 2200 fps.
Effective Point Target Casualty Range of a given firearm/optic/load is that which the individual marksman can engage with a hit percentage of no less than 50% and deliver a projectile with sufficient mass and velocity to reach vital organs and produce a potentially lethal wound.
Despite the stricter accuracy standards, velocity and energy will usually determine the Effective Point Target Rifle Range. The 5.56 will pack plenty of velocity out to 300+ yards, but lacks the mass and therefore the energy. The 7.62x39 has the opposite problem. We run into accuracy limitations when determining Effective Point Target Casualty Range because many of our rifle rounds are capable of producing casualties to much farther out than most of us can identify targets and place rounds under realistic conditions.
It is important to note that when we discuss handguns or older straight-walled blackpowder cartridges producing less than 2200 fps at the muzzle, there is no Effective Point Target Rifle Range. With handgun velocities, we are just poking holes. The caliber and depth of penetration is all that matters. Energy does not contribute significantly to wounding at these velocities and our effectiveness has dramatically decreased such that at this point, we are mostly creating casualties, so there is no energy threshold for Effective Point Target Casualty Range. It is also important to note that we are not discussing bullet design at this point. We would be inferring a relative performance standard assuming we compare projectiles of similar construction.
With that in mind, the M855 leaving a 20 inch barrel @ 3020 fps looks something like this:
Effective Point Target Rifle Range = 100 yards (2749 fps/1040fpe)
Effective Point Target Casualty Range = (presumably) ~550 yards
With hunting season upon us, it might be interesting to see what the effective ranges of your hunting load are:
.308 Win 150 gr Hornady SST @ 2750 fps from a 20 in barrel
Effective Point Target Effective Rifle Range = 300 yards (2200 fps/1600 fpe)
Effective Point Target Casualty Range = I only have a 3.5x Trijicon TA11J, and haven't had the time or ammo to really stretch this rig, so I am going to limit shots to my Effective Rifle Range. But in theory, this load could produce a potentially lethal wound about as far out as you could hit with it, say, at least 750 to 800 yards, at which point it will be transonic, but still packing the mass and momentum of a 147 gr 9mm round.
Our knowledge of terminal ballistics has shown us the importance of velocity in wounding. We now know that energy as a figure for determining potential trauma is limited. For those with even an superficial understanding of basic physics concepts, the impulse matters as much as the amount of energy. The impulse is the amount of time it takes energy to be transferred. A projectile has energy as mass and velocity. The only way it uses this energy is through losing mass or velocity. The amount of time this takes is crucial in determining how your projectile interacts with living tissue, and is a function of velocity.
We all know what "hydrostatic shock" is, or are at least aware of it as a concept. The pressurized shock wave that moves away from the impact of a projectile in a liquid or semi-liquid medium can be demonstrated to awesome effect simply by shooting milk jugs filled with water. This effect is present regardless of the velocity of the projectile. However, our tissue is thankfully much more resilient to these forces than plastic milk jugs. Living tissue stretches and deforms, then returns to normal with little to no permanent damage. This allows the body to absorb an incredible amount of energy without damage because the impulse is too long. For this reason, energy is irrelevant as a indicator of effectiveness with projectile impacts under 2200 fps. At velocities above 2200 fps, the impulse is too short, the impact too violent. Tissue can not stretch or deform far or fast enough. It tears and breaks apart, damaging or destroying tissue for several inches beyond the path of the actual projectile. This is what makes a rifle a rifle and a handgun a handgun. Speed kills. Whereas about 1 in 4 people shot in the torso with a handgun dies, about 1 in 4 people shot in the torso with a rifle lives. Hollywood lied to you. High velocity rifles are orders of magnitude more effective than handguns.
So our first indicator of effectiveness should be the range to which our weapon will be truly effective, bring shock and awe, and "kill like a rifle." For this, we want 1000 foot pounds of energy on target and the velocity to use it, so at least 2200 fps. All of this power does no good if the average shooter can't find his mark, so our definition of effective range should include the ability to realistically find, range, and engage with a high degree of accuracy. So for the purposes of this discussion, we are going to say that:
Effective Point Target Rifle Range of a given firearm/optic/load is that which the individual marksman can identify, range, and engage with a hit percentage of no less than 75% and deliver 1000 foot pounds on target with at least 2200 fps.
Effective Point Target Casualty Range of a given firearm/optic/load is that which the individual marksman can engage with a hit percentage of no less than 50% and deliver a projectile with sufficient mass and velocity to reach vital organs and produce a potentially lethal wound.
Despite the stricter accuracy standards, velocity and energy will usually determine the Effective Point Target Rifle Range. The 5.56 will pack plenty of velocity out to 300+ yards, but lacks the mass and therefore the energy. The 7.62x39 has the opposite problem. We run into accuracy limitations when determining Effective Point Target Casualty Range because many of our rifle rounds are capable of producing casualties to much farther out than most of us can identify targets and place rounds under realistic conditions.
It is important to note that when we discuss handguns or older straight-walled blackpowder cartridges producing less than 2200 fps at the muzzle, there is no Effective Point Target Rifle Range. With handgun velocities, we are just poking holes. The caliber and depth of penetration is all that matters. Energy does not contribute significantly to wounding at these velocities and our effectiveness has dramatically decreased such that at this point, we are mostly creating casualties, so there is no energy threshold for Effective Point Target Casualty Range. It is also important to note that we are not discussing bullet design at this point. We would be inferring a relative performance standard assuming we compare projectiles of similar construction.
With that in mind, the M855 leaving a 20 inch barrel @ 3020 fps looks something like this:
Effective Point Target Rifle Range = 100 yards (2749 fps/1040fpe)
Effective Point Target Casualty Range = (presumably) ~550 yards
With hunting season upon us, it might be interesting to see what the effective ranges of your hunting load are:
.308 Win 150 gr Hornady SST @ 2750 fps from a 20 in barrel
Effective Point Target Effective Rifle Range = 300 yards (2200 fps/1600 fpe)
Effective Point Target Casualty Range = I only have a 3.5x Trijicon TA11J, and haven't had the time or ammo to really stretch this rig, so I am going to limit shots to my Effective Rifle Range. But in theory, this load could produce a potentially lethal wound about as far out as you could hit with it, say, at least 750 to 800 yards, at which point it will be transonic, but still packing the mass and momentum of a 147 gr 9mm round.
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