7.62 NATO/.308 "margin of error"
- Thread starter ramsfan
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courtgreene
Member
I'm not sure what you're asking, but whatever the question, I'd think the answer wouldn't be specific to this chambering. I think if it is true of an FMJ in 7.62 (.30) then it would be true of FMJ in pretty much anything.
7.62x51NATO
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Diggin' the name!
7.62 Nato and 7.62x51NATO....that could get confusing. 
ramsfan, as taliv said, look up hydrostatic shock.
More complicated than I can fully understand or explain, but basically with high velocity rounds, the projectile creates a pressure wave in the fluid around the wound channel, remember, we humans are like 70% water. That pressure wave can disrupt the organs, including brain, or even cause hemorrhaging.
AFAIK most high power rifle rounds will do this. Few handgun rounds though.
ramsfan, as taliv said, look up hydrostatic shock.
More complicated than I can fully understand or explain, but basically with high velocity rounds, the projectile creates a pressure wave in the fluid around the wound channel, remember, we humans are like 70% water. That pressure wave can disrupt the organs, including brain, or even cause hemorrhaging.
AFAIK most high power rifle rounds will do this. Few handgun rounds though.
I guess what I am asking is if this .30 caliber full metal jacket bullet will blow a 3 or 4 inch hole through the torso of an unfortunate recipient or scramble all their insides? Or will it punch a caliber sized hole (which doesn't seem like much considering the reputation of this round)?
Depends on the range and particular bullet as well as the rifle it was fired from. At high velocity, the bullet will yaw and often fragment at the cannelure which makes a pretty nasty wound channel. Even if it doesn't fragment, it will often yaw with still rather effective results. The problem with FMJ rounds is that they are inconsistent on a good day. The good news is that since you are not a military combatant, you are not bound by the Hague conventions and can defend you and yours with expanding bullets. I wouldn't dream of carrying FMJ rounds in a personal handgun that I might defend myself with and my rifle ammo is no different. I have a LOT of bonded soft point rounds that are much more of a sure thing than FMJ.
^^^ Exactly! If FMJ bullets were that great or consistent, I can't imagine why ammunition makers invest a whole lot of $$$ on good, effective hunting bullets. My choice? Good quality premium bonded soft points for social rifles, and quality soft or hollow points for sidearms.
Matthew Courtney
Member
.308 fmj bullets tend to penetrate further than .223 fmj bullets before tumbling, so effectiveness variances would likely relate to the angle and location of the wound path. I am a Barnes TTSX 168 gr believer because I like to leave little to chance.
30Cal
Member
If you're talking about missing; a miss is still a miss.
Sam1911
Moderator Emeritus
No, he's not talking about missing.
He's asking, just as an illustration, if I put a bullet through a living being and I do not strike the heart, but my bullet passes within 2-3" of it, will the heart be critically damaged by the bullet passing near?
Or must the bullet actually impact/penetrate some critical tissue in order to wound/kill that tissue?
Roy Weatherby was a huge proponent of the hydrostatic shock idea, whereby body structures would actually be seriously compromised from the instantaneous hydraulic pressure spike inside the body caused by a high-speed bullet impacting.
Another possible compounding or competing idea is "temporary stretch cavity" concept. When a bullet strikes, tissues in the surrounding area tend to stretch out like a balloon and then snap back rapidly as the bullet passes. The area displaced is the temporary stretch cavity and the much smaller channel of crushed and torn tissue left behind the bullet is the permanent wound cavity. Obviously the permanent wound cavity causes massive damage and death to tissues, but how effective the temporary stretch cavity is in actually breaking down the tissues affected is hotly debated.
MachIVshooter
Member
Depends. Most body parts, including internal organs, are pretty elastic and can be squished/stretched substantially without serious damage beyond capillary rupture (petechiae/bruising). But some, like the liver, are inelastic and very easily damaged (and will bleed a great deal).
I would say, though, that generally speaking, if the bullet passes a couple inches away from a given organ/structure, that organ/structure is not likely to sustain much damage, if any. Many people have taken rifle bullets that missed things like the aorta by mere millimeters and survived with just punctured lungs and general tissue damage.
Now, switch to an expanding bullet, and the game changes a bit. You have a much bigger wound channel and often secondary projectiles as the bullet sheds pieces. If you've ever hunted big game, you've seen the tremendous damage an expanding rifle bullet can do.
Thank you all for your comments. A .30 caliber fmj bullet just seems like a small bullet to have reputation in our military history. One could easily get the notion from a lot of what's out there that no enemy ever survived a torso hit from one of these rounds.
High pressure vessels carrying blood tend to be TOUGH.
In order to incapacitate a target you have to get a CNS shot or allow enough blood to leave the body to render an unconscious state.
Stretching an artery, or heart (which is tough muscle), will not release blood, nor is it a CNS shot.
This being said, there ARE tiny little veins and arteries branching off the main arteries leaving the heart, which loop back and supply blood to the heart muscle, proper. Severing THOSE (which are not nearly as tough or resilient as the "parent" artery) WOULD effectively stop the heart from functioning after a period of time, as it would no longer supply oxygen to the heart muscle proper.
But we're talking about vessels that are smaller in diameter than a toothpick and heavily "shielded" by the structure around it.
So no, you are not very likely at ALL to incapacitate someone due to hydrostatic shock or temporary stretch cavity.
This being said, a close shot to a CNS point (base of the skull) will render a person unconscious or paralyze them for quite a long time. Look up the miami shootout - a federal agent took a 223 round through the neck, missed the spine but the passing of the bullet "shocked" the spinal cord sufficiently to paralyze him for a great deal of time.
So ... plausible.
But not very likely.
In order to incapacitate a target you have to get a CNS shot or allow enough blood to leave the body to render an unconscious state.
Stretching an artery, or heart (which is tough muscle), will not release blood, nor is it a CNS shot.
This being said, there ARE tiny little veins and arteries branching off the main arteries leaving the heart, which loop back and supply blood to the heart muscle, proper. Severing THOSE (which are not nearly as tough or resilient as the "parent" artery) WOULD effectively stop the heart from functioning after a period of time, as it would no longer supply oxygen to the heart muscle proper.
But we're talking about vessels that are smaller in diameter than a toothpick and heavily "shielded" by the structure around it.
So no, you are not very likely at ALL to incapacitate someone due to hydrostatic shock or temporary stretch cavity.
This being said, a close shot to a CNS point (base of the skull) will render a person unconscious or paralyze them for quite a long time. Look up the miami shootout - a federal agent took a 223 round through the neck, missed the spine but the passing of the bullet "shocked" the spinal cord sufficiently to paralyze him for a great deal of time.
So ... plausible.
But not very likely.
Given a straight through wound, no yawing or fragmentation or bones involved, would the difference between a .30 fmj and a .223 fmj be significant?
Is the caliber difference enough that the .30 caliber wound would be expected to bleed that much more or more quickly ?
Is the caliber difference enough that the .30 caliber would likely hit something or things that the .223 missed thus producing a more effective wound?
Is the caliber difference enough that the .30 caliber wound would be expected to bleed that much more or more quickly ?
Is the caliber difference enough that the .30 caliber would likely hit something or things that the .223 missed thus producing a more effective wound?
Sam1911
Moderator Emeritus
That's a good question, and heartily debated. Most folks seem to intuitively believe it must be so, based on the amount of energy carried by the bullet. The problem is that only some (relatively small) portion of that energy actually gets transferred into the target (damaging tissue) before both projectiles exit and continue on. There is more friction involved with the larger surface area (and frontal area, sort of, kind of) of the larger bullet, but how important that is is up for debate.
A bigger hole (pair of holes, really) is a bigger hole (again, pair of holes). But .30 isn't all that much bigger than .224, in truth.
Hardly. Considering the same center-line of the bullet passing through the target, the outer edge of a .308" bullet will clip a structure that is a full 0.042" farther out from that center line than a .224" bullet! That would seem to be orders of magnitude smaller than the precision error introduced by the inherent inaccuracy of the rifle, and MANY orders less than the basic aiming error induced by the shooter!
We laugh about that a lot in the competition circles -- where a .45 bullet cuts a scoring ring that a 9mm might just barely have missed.
Thank you Sam. Any thoughts on why or if a 7.62 NATO/.308 fmj wound (without yawing) would incapacitate more effectively than an identical shot with a 9mm pistol?
Here's my line of thought - the common knowledge is that the rifle will always be better than a pistol (even if the pistol bullet is larger). If the permanent cavity size is smaller with the rifle round and the temporary stretch cavity (fmj bullet, not yawing) has little if any effect on elastic tissues, it seems that there would be very little difference in the resulting wound.
Here's my line of thought - the common knowledge is that the rifle will always be better than a pistol (even if the pistol bullet is larger). If the permanent cavity size is smaller with the rifle round and the temporary stretch cavity (fmj bullet, not yawing) has little if any effect on elastic tissues, it seems that there would be very little difference in the resulting wound.
I guess what I'm kind of hung up on is that the temporary cavity is touted as the significant wounding mechanism with a rifle (the reason rifle bullet wounds are so distinctive from handgun wounds and are more destructive with a smaller bullet than a handgun).
But then there is all the information that says the temporary cavity has little or no effect on elastic tissues. This seems to take away the reason a rifle round would be more damaging.
But then there is all the information that says the temporary cavity has little or no effect on elastic tissues. This seems to take away the reason a rifle round would be more damaging.
ramsfan - I've heard (anecdotal) evidence that a rifle bullet passing NEAR a bone could shatter the bone.
Elastic tissue will rebound. Bone will not.
Also, if a rifle round breaks up in transit, you now have two wounding channels. (enter the claim to fame of 5.56, and why SS109 and other penetrating rounds do less damage than their soft-core counterparts).
Tumbling creates a much larger permanent cavity in addition to the above. Enter the nastiness of 5.45x39mm ammunition with the hollow front cavity in the nose of the bullet. Forces the tumble, which promotes rapid break up of the projectile, and ugliness results.
Elastic tissue will rebound. Bone will not.
Also, if a rifle round breaks up in transit, you now have two wounding channels. (enter the claim to fame of 5.56, and why SS109 and other penetrating rounds do less damage than their soft-core counterparts).
Tumbling creates a much larger permanent cavity in addition to the above. Enter the nastiness of 5.45x39mm ammunition with the hollow front cavity in the nose of the bullet. Forces the tumble, which promotes rapid break up of the projectile, and ugliness results.
Driftertank
Member
Ah, but you see, while major structures themselves may not sustain more permanent damage from the passing of a bullet, smaller vessels in and around the structures will rupture, leading to more rapid exsanguination. And then theres the phenomenon of PAIN...
As mentioned before, the "temporay wound cavity" can be thought of as severe bruising of internal organs and musculature, characterised by minor tearing of tissue and capillaries, and your nerve endings will report all this damage dutifully. The damaged muscle fibers in the area immediately around the wound will exhibit loss of effectiveness as well.
So while temporary wound cavity may not directly result in more rapid lethality, it certainly results in less effective use of the body parts affected. Which reduces the ability of the target to pose a threat.
As mentioned before, the "temporay wound cavity" can be thought of as severe bruising of internal organs and musculature, characterised by minor tearing of tissue and capillaries, and your nerve endings will report all this damage dutifully. The damaged muscle fibers in the area immediately around the wound will exhibit loss of effectiveness as well.
So while temporary wound cavity may not directly result in more rapid lethality, it certainly results in less effective use of the body parts affected. Which reduces the ability of the target to pose a threat.
Sam1911
Moderator Emeritus
An interesting question. Some would say that a rifle FMJ that hits at, say 2,500 fps and bores a perfectly straight through wound would not truly be much more devastating than a similarly-sized FMJ pistol bullet that hits at 1,200 fps and bores a perfectly straight through-and-through wound path.
Others will expect the rifle round to cause far more incapacitation.
The truth is probably that things are rarely quite so perfectly equal. A rifle round going that fast which does ANYTHING to deviate from a perfect drill-hole path is going to dump a lot of energy into destroying tissues, through yaw and/or fragmentation, etc.
Others will expect the rifle round to cause far more incapacitation.
The truth is probably that things are rarely quite so perfectly equal. A rifle round going that fast which does ANYTHING to deviate from a perfect drill-hole path is going to dump a lot of energy into destroying tissues, through yaw and/or fragmentation, etc.
Many a deer have suffocated as their lungs filled with blood when a bullet passed mere inches from their hearts vs. hitting the heart and having them fall over dead.
30 cal bullets seem to pass through more than expand and leave large holes. There's a shock value, but you still have to hit something vital.
30 cal bullets seem to pass through more than expand and leave large holes. There's a shock value, but you still have to hit something vital.
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