Stopping Power
Having some shooting related thoughts, they’re a bit nerdy so if you don’t shoot, stop here.
I’ve seen a lot of debates recently about “stopping power” and have some serious doubts about what I have read. I only have limited experience on animals and hope never to see a person getting shot, but still, the doubts remain.
I’ve probably inadvertently plagarised a few people’s thoughts here, but have added a few of my own too.
I’ll start with a usual gunzine article “14 inch Naval gun or .22 BB Cap, which is best?”
It makes sense to me that the Naval gun will do more damage on a target and have “better stopping power” than a bb cap,
BUT:
Does a slight increase in bullet diameter have a statistically significant increase in instant incapacitation? and, at what increment of bullet diameter for a given sectional density and velocity does that become statistically significant?
Then, how much of the advantage in incapacitation is off set by a lower hit probability from a heavier, harder kicking gun and a lower number of shots carried by each person?
Even fatal hits with none expanding bullets, lets say through the heart, give a critter about 40 to 60 seconds of running about as though nothing was really wrong.
All that I have seen and read suggests a massive variability in wounding effect from identical hits on identical animals with identical bullets at identical velocities.
As an example, the one and only shot that caused an instant knockdown with a chest shot on cattle in the trials that lead to the recommendation that .45 was the minimum acceptable caliber for a US service pistol, was with
Wait for it!
Here you are: .30 Luger!
I have read Peter Capstick joking that stopping power varied with local tides and the pollen count.
With African big game, kills are usually by a shot into the heart, Brain shots are for those with nerves of steel, as the target area is small and on Elephant, Buffalo and Rhino, it is also well protected. A charging elephant holds its’ head back and presents several feet of bone to penetrate before reaching the brain.
Shots to the Skeleton, for example the shoulders may drop an animal allowing a follow up fatal shot.
Interestingly, Elephant and Buffalo culling was (?is) frequently carried out using the L1A1 (FN FAL) with military 7.62mm 156 grain FMJ.
For Hunting, 6.5mm 160 grain round nose FMJ had the penetration for some use on elephant, and 140 grain 6.5mm is still used for much European elk (moose) shooting. Unfortunately, the pencil like 160 grain bullet lacked structural strength, being prone to bending and going off line on its long journey to the vitals.
From my limited engineering view point, the heavy calibres had the advantage in having a less slender and therefore more rigid structure for a similar sectional density, when compared to the likes of a 6.5mm.
Possible lesser advantages were a lower ratio of surface area per grain of bullet weight, therefore slightly less drag per grain than the small diameter bullet, and proportionately less low density jacket material in their construction.
The much more massive bullet would also be carrying more energy at the end of its long travel through guts, bone and muscle, so was probably better able to break a major bone, say a shoulder or a pelvis.
I have left out the size of wound channel and “shock effect”. “Shock Effect” because even the big “stopping” rounds such as .577 and .600 are still too small compared to the size of the animal to set up a hydrostatic shockwave similar to that experienced by a rodent being hit with a hyper velocity .22. I would argue that the same is true with military rounds and human sized targets which have their adrenaline flowing.
With diameter of wound channel. I remain to be convinced that one or two millimeters change in diameter of either a solid bullet intended for big game, or a tumbling military ball round will make a statistically significant difference.
Infact, the shock wave due to a bullet’s passage will obey the inverse square law, as the distance from the bullet doubles, so the energy of the shockwave will reduce by the square root.
As an analogy, heat two bullets of different calibers to say 200 or 250°C (any higher and any solder will start to melt). Quickly tip them onto a heat resistant surface a reasonable distance apart, and, quickly again, see if you can detect much difference in the radiated heat at a given distance. The skin on the back of your hand is a pretty good heat detector.
Like shockwaves, the radiated heat decays with the distance according to the inverse square. (if you double the distance, the area is squared).
Don’t however confuse the contained heat in the bullets, this is analogous to momentum and is directly proportional to bullet mass (assuming equivalent proportions of jacket and core between the two bullets, as these materials will have different specific heat capacities). Momentum would only be fully transmitted to a target if the bullet failed to exit, and an exit wound is a good path for quick blood loss, leading to loss of consciousness.
The changes in military rifle caliber that I have seen suggested would go from 5.56mm diameter to something like 6.5mm or 6.75mm diameter. To me this sounds like a waste of time money and effort. I don’t think it will give a statistically significant increase in number and speed of incapacitations.
Go on someone, give me hard evidence that I am wrong. I’ll even give you a head start by setting the bar low at 95% significance, one tailed T Test.
I’ve seen a lot of debates recently about “stopping power” and have some serious doubts about what I have read. I only have limited experience on animals and hope never to see a person getting shot, but still, the doubts remain.
I’ve probably inadvertently plagarised a few people’s thoughts here, but have added a few of my own too.
I’ll start with a usual gunzine article “14 inch Naval gun or .22 BB Cap, which is best?”
It makes sense to me that the Naval gun will do more damage on a target and have “better stopping power” than a bb cap,
BUT:
Does a slight increase in bullet diameter have a statistically significant increase in instant incapacitation? and, at what increment of bullet diameter for a given sectional density and velocity does that become statistically significant?
Then, how much of the advantage in incapacitation is off set by a lower hit probability from a heavier, harder kicking gun and a lower number of shots carried by each person?
Even fatal hits with none expanding bullets, lets say through the heart, give a critter about 40 to 60 seconds of running about as though nothing was really wrong.
All that I have seen and read suggests a massive variability in wounding effect from identical hits on identical animals with identical bullets at identical velocities.
As an example, the one and only shot that caused an instant knockdown with a chest shot on cattle in the trials that lead to the recommendation that .45 was the minimum acceptable caliber for a US service pistol, was with
Wait for it!
Here you are: .30 Luger!
I have read Peter Capstick joking that stopping power varied with local tides and the pollen count.
With African big game, kills are usually by a shot into the heart, Brain shots are for those with nerves of steel, as the target area is small and on Elephant, Buffalo and Rhino, it is also well protected. A charging elephant holds its’ head back and presents several feet of bone to penetrate before reaching the brain.
Shots to the Skeleton, for example the shoulders may drop an animal allowing a follow up fatal shot.
Interestingly, Elephant and Buffalo culling was (?is) frequently carried out using the L1A1 (FN FAL) with military 7.62mm 156 grain FMJ.
For Hunting, 6.5mm 160 grain round nose FMJ had the penetration for some use on elephant, and 140 grain 6.5mm is still used for much European elk (moose) shooting. Unfortunately, the pencil like 160 grain bullet lacked structural strength, being prone to bending and going off line on its long journey to the vitals.
From my limited engineering view point, the heavy calibres had the advantage in having a less slender and therefore more rigid structure for a similar sectional density, when compared to the likes of a 6.5mm.
Possible lesser advantages were a lower ratio of surface area per grain of bullet weight, therefore slightly less drag per grain than the small diameter bullet, and proportionately less low density jacket material in their construction.
The much more massive bullet would also be carrying more energy at the end of its long travel through guts, bone and muscle, so was probably better able to break a major bone, say a shoulder or a pelvis.
I have left out the size of wound channel and “shock effect”. “Shock Effect” because even the big “stopping” rounds such as .577 and .600 are still too small compared to the size of the animal to set up a hydrostatic shockwave similar to that experienced by a rodent being hit with a hyper velocity .22. I would argue that the same is true with military rounds and human sized targets which have their adrenaline flowing.
With diameter of wound channel. I remain to be convinced that one or two millimeters change in diameter of either a solid bullet intended for big game, or a tumbling military ball round will make a statistically significant difference.
Infact, the shock wave due to a bullet’s passage will obey the inverse square law, as the distance from the bullet doubles, so the energy of the shockwave will reduce by the square root.
As an analogy, heat two bullets of different calibers to say 200 or 250°C (any higher and any solder will start to melt). Quickly tip them onto a heat resistant surface a reasonable distance apart, and, quickly again, see if you can detect much difference in the radiated heat at a given distance. The skin on the back of your hand is a pretty good heat detector.
Like shockwaves, the radiated heat decays with the distance according to the inverse square. (if you double the distance, the area is squared).
Don’t however confuse the contained heat in the bullets, this is analogous to momentum and is directly proportional to bullet mass (assuming equivalent proportions of jacket and core between the two bullets, as these materials will have different specific heat capacities). Momentum would only be fully transmitted to a target if the bullet failed to exit, and an exit wound is a good path for quick blood loss, leading to loss of consciousness.
The changes in military rifle caliber that I have seen suggested would go from 5.56mm diameter to something like 6.5mm or 6.75mm diameter. To me this sounds like a waste of time money and effort. I don’t think it will give a statistically significant increase in number and speed of incapacitations.
Go on someone, give me hard evidence that I am wrong. I’ll even give you a head start by setting the bar low at 95% significance, one tailed T Test.
posted by Keith at 5:49 p.m.
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