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[ARCHIVED THREAD] - quick newbie question (Page 1 of 2)
Posted: 9/29/2002 10:21:58 PM EDT
| what is grain in ammo? like whats the differance between 63 grain and 55grain? |
7000 grain in one pound 
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we only responded quickly because we have no life outside ar15.com and related ventures  higher grain "kinda" means more lethal. for the 5.56 NATO round, the lethality is less in the mass of the bullet than in its fragmenting properties. tons of info at ammo-oracle.com. i can't go over enough of it here, and most poeple will just say "read the ammo faq!" super great resource. |
1 metric gram = 15.4323583529414 grains 1 ounce = 437.5 grains courtesy of www.omnis.demon.co.uk/english/conversn/convjvsc.htm?source=homepage&display=table&format=fixed&cover=beige&screen=%23FFFFFF&text=%23000000&ccover=blue&cscreen=white&ctext=%23000000&cftext=%23ffff00&lang=1®d=false&url=null&link=null&adnum=032&nav=nav6&ver=5.0%20%28Windows%3B%20en-US%29&vermaj=5&vermin=5&jsver=1.5&bver=6&searcharg=null&jumpto=null&favpag=null |
| if two bullets are traveling at the same speed the heavier one will have more foot pounds behind it. this means more knock down power. their is a formula for this but i don't know it off the top of my head. also, the lighter bullet will travel faster with the same powder charge. |
KE = 1/2 mv^2 where: KE is kinetic energy, 1/2 is a constant, 0.50, m is the mass of the particle, v is the velocity of the particle |
So Kinetic Energy equals .5 X 62 grains x 2700 feet per second squared equals 225990000 grain feet per second? |
almost. units would be grains ft^2/s^2 and "foot pounds" implies that there's an acceleration divided out, hence you lose the ft/s^2. i'm not sure what acceleration they're dividing out to get "foot pounds" (or grain feet, or foot-grains, etc). i'll try to look it up tomorrow, but this is my last post of the night. i've got PT in the morning, and really should get to bed so i can make it okay |
NO NO NO NO NO!!! First, there is NO SUCH THING AS "KNOCK-DOWN POWER". What bullets do when they hit flesh is cause TISSUE DAMAGE.  Certainly, a heavier bullet moving the same speed as a lighter bullet will have more kinetic energy, and more momentum. But that is only one component in a very complex calculation. Bullet design, construction, and materials play a HUGE part in the size, shape, and depth of the wound channel caused by a bullet strike. You have to be very careful when making generalizations! Please read www.ammo-oracle.com for more info. -Troy |
oh. didn't know it was weight and not mass. which means units on grains is kg m/s^2, so it comes out quite nicely as "foot pounds" when you convert. yay! |
Pardon me, Troy, I think there is an effect of the impact of a round into tissue that relates to 'knockdown power.' I have hit many animals with a variety of rounds, and some rounds do actually 'knockdown' the animal. The effect is based upon the translation of the momentum of the bullet into the flesh of the target. Some bullets tend to 'knockdown animals more easily than others. Shot placement also seems to be a determining factor along with the mass of the animal, its position when struck, the targets motion relative to the impact vector, displacement area based upon the bullets energy relative to the target's mass, etc. You shoot a bull moose with a .22 LR and it probably won't be knocked off its feet. However, shooting a field mouse with that same .22 LR will produce a nice, spinning, death dance. I have knocked several 200-250 pound boars completely off their feet with a .223. They literally were knocked to the ground from the impact energy. They subsequently got up and walked away, but they definately hit the ground hard first. They also hit in the same direction of travel of the bullet. It was obvious the impact is what knocked them over. One dramatic illustration was a sow in the 225 pound class that left a perfect outline of the left side of her body in the mud after being hit in her right shoulder. |
No, they weren't. A .223 bullet doesn't have enough momentum to knock over a boar. If they appeared to be "knocked over" it was a reaction to being hit, perhaps a spasam or loss of muscle control. 75 gr/7000 * 2750 fps = 200 lbs * X fps Solving for X gives 0.15 fps. That's assuming ZERO energy is lost deforming the bullet or damaging tissue. And that the body is free to move with no resistance. And using the muzzle velocity, not the impact velocity. OK, maybe the nudge was enough to knock them off balance and they fell over. |
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Mike_L, Don't start grabbing the calculator on me.  I have seen it happen more than once. Whether it is from the 'nudge' or the nervous system shock, I don't know. I do know that they can be knocked completely over onto their side upon impact. Not just nudged, knocked off their feet. You would think someone had shoved them over on to their side.Most of the time, the majority of the impacts result in a the classic stumble, but a solid shoulder hit is what seems to cause them to be knocked over. The sow that was hit, and left such an interesting body cast in the mud, was trailed for 400yds since the round turned and exited her throat. Coyotes will actually spin on their axis, from the impact of a round. My neighbor hit one with a .30-06 in the gut and it was turned the opposite direction from the impact energy. Looked like someone had tied a rope to its legs and yanked it around. |
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u guys are really explaining it hehe=)..im plannin to buy a Ar-15 from bushmaster ,mostlikely .233 caliber.Can i use .233 bullets with different grains on the same barrel...like if i want to use 55 grain for target practice and leave 63 grain at home for defense purposes/shtf with the same barrel? would that damage my barrel? p.s. thnx for the help |
Technically you can't. You see, for some reason--and reloaders know this--the diameter of the bullets is actually .224"  I'm not making that up! To keep life simple I personally use 62 gr at the range and keep 62 for the gun at home. |
Sorry. Should have said that I'm too lazy to rezero my sights everytime I go to and from the range. Folks can and do shoot everything from 45 to 70 gr, but everytime you change ammo--whether it's factory or reloaded--your working with new ballistics and will have to range test and rezero--readjust--your sights. Your zero and accuracy can vary even if you stick to 55 gr weight bullets and switch brands from say Winchester to American Eagle. Therefore I buy ammo in 1,000 round cases whenever I can find and afford it (Over time, I've decided to stick with 62 gr. IMI M855). When I break open a new case, I verify my zero at the range. If I wanted to I could go out, buy some 55 grain ammo, say 100 rounds. Take it to the range, fire about 18 rounds to zero for that specific ammo--remembering to keep track of the number and direction of clicks I adjust my sights off the 62 gr zero--fire all 100 rounds and go home. Once home, I have to recall what sight adjustments I made and reverse the changes. |
I don't know if talbalos is yanking your chain for calling it .233 instead of .223, but yes you can shoot different weight bullets through your barrel, yes they may/will have different trajectories, hence points of impacts, will more than likely have different muzzle velocities, will have different accuracy performances and yes the actual bullet diameter is .224. This allows the bullet obturate into the grooves, around the lands. Depending on the twist rate you may find that a certain range of bullet weights may perform better (give better accuracies) at certain ranges. Generally speaking heavier bullets will be less influenced by outside forces and provide a flatter trajectory and therefore provide better long range accuracy. Heavier bullets, generally speaking, have a longer bearing surface, slower velocities and require a faster twist barrel to stabilize. The converse is true, generally speaking, with say a lighter weight range of bullets. The reason I caveat everything is it's the bullets BC (Ballistic Coefficient) that affects it's trajectory. The BC is strongly influenced by weight (mass) but also by shape. It is possible for a lighter bullet of the same caliber to have a higher BC (fly flatter given the same velocities) than a heavier one. Totally confused? Get a good reloading manual and it may explain it better. |
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H3at, Here's my .02, increased weight doesn't necessarily mean more lethality, even if at the same speed as a lighter round, it depends on shape, bullet construction ect. For example, on porcupines and other cuddly pests, 62 grain wolf fmj sails right through with no fragmentation I can tell of, but my 55gr ballistic tips blow the little buggers right open, and my loads are very mild. Here's the formula (big #s rounded off) for calculating ft. lbs of energy, you can check them against ammo manufacturers tables, this is dead on within 1 or 2 lbs either way. --------------------------------------------- Velocity SQUARED -(VxV) multiplied by the bullets weight in grains divided by 450 000 Ex. >30-06 [email protected]. 3000x3000=9 000 000 9 000 000 x 150= 1350000000 1350000000 divided by 450 000= 3000 ft lbs. note that the fact the end energy is the same as the start velocity is a co-incidence And in my 2 cents, there are so many myths about (knock downs) Personally I think it can be energy transfer on the target, loss of motor control or shock, flinching on part of the target, weight and center of gravity of target relitive to shot placment and power or all the above. All I know is when you hit a squirrel with a .30 carbine he'll do a backflip off the tree, I don't see too many squirrels practicing backflips on their own. |
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wow so there are alot of factors in a bullets lethality..thnx for the info well im planing to get a bushmaster rifle 16" barrel most likely it'll be chrome lined 1:9 turns .223 caliber.What brand and grain would be good to use for at the range and at home for self defense and good accuracy..I wouldnt mind spending a pretty penny for my ammo thnx for the help btw i will be using a FAB-10 lower =( i live in cali so its the only choice i got |
Sounds like it's time for the "Read the AR15.com Ammo FAQ" post. ;) |
It's kind of confusing because when people talk about weight and mass going back and forth from the metric system we use different units as interchangeable. It is said that 1 kilogram = 2.2 pounds. Pounds is a unit of weight or force while kilograms is a unit of mass. What should really be said is that a kilogram exerts a force of 9.8 Newtons here on Earth, which is equal to a force of 2.2 pounds (acceleration due to gravity = 9.8 meters/sec^2 here on earth). F=MA. I think the old English unit for mass is called a slug. |
"Damn the laws of physics, FULL SPEED AHEAD!" Have you ever seen the video where the subject wears a Level IV vest and (voluntarily) takes a 7.62x39 into the chest? Slight movement, not exciting. Certainly no "knock down." Sorry. |
I could be wrong here, but if I recall correctly, it was a 7.62 NATO that he was shot with. Other than that, Tatja is correct. This was 100% energy transfer at point blank range. No knock down. I think the only thing that happened was the subject ran to change his underwear. |
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Another way to think of it is: You (with your gun) are accelerating the bullet. The game animal is decelerating it. The energy required to accelerate the bullet is the same the bullet gives up when it decelerates(actually less, due to the loss of bullet speed over distance, but we will ignore this for simplicity). If the bullet has enough energy to knock over a 250 pound animal then it should knock over a person that weights less than 250 lbs as they fire the bullet. My rifle and I weight less than 185 lbs. When I fire my AR, my AR and I move very little. Certainly nowhere near being pushed over. My take (this is only my unscientific opinion now) on the animals falling over when hit is: when you hit a bone structure that is tied closely to the spine it stuns them for a moment. I think like hitting your funny bone (just guessing here). I haven't shot enough big game to come to a definitive conclusion, but when I see them hit in the shoulder bone, pelvis, and sometimes ribs (and obviously the spine) they go down right away. They may not stay there but they almost always go down or at least stumble. Whereas when they are hit well, but miss major bones they quite often don't fall, but can run for many yards as if not hit. Disclaimer: These are my observations and are in no way repeatable scientific tests. The test subjects were N. MI whitetail of 125 - 175 pounds. BTW: There was a defense "expert" I read of a few years ago that was promoting a shot to the pelvis as a "stopper" since it is a larger target than the head. I can't remember where I read this though. Kent |
At-Muther phaquing-zactly. There is a thing called hydrostatic shock that will literally shock everything inside a contained volume, kind of like the old water filled milk jugs. The human skin is a little more elastic and won't burst but the interternals are still all FU. Water acts like a solid when compressed. The victim drops like a sack of potatoes off a flat bed....sometimes even with a bounce. |
Sorry, this is a myth. It started with the Strasbourg Goat Experiments. "Hydrostatic shock" doesn't really play much into stopping aggressive subjects. |
Again my opinion is totally non-scientific. I was not intending to claim hydrostatic shock. I'm not a big believer in that. I was thinking more about energy transfer through the solid bones closely tied to the spinal cord, but only as a stunning agent not a stopping agent. The only other benefit I see in shooting through bone is the secondary projectiles it causes, which I think speeds up expiration. I'm only relating hunting expiriences, not the stopping of things that can/will do me bodily harm if I don't effect an immediate stop. The bullets I used where deep penetrating hunting bullets that don't typically fragment, so the secondary projectiles caused by shooting through bone I think were very beneficial. The incident that completely blew my opinion of hydrostatic shock was a shot by my brother-in-law at a deer less than 50 yards away with a 180 grain bullet from a .30-06. The bullet entered behind the rib cage traveled cross ways through the chest cavity and exited the far shoulder of a 125 pound deer. The deer ran at the shot and didn't stop until it travelled 75 plus yards and wedged itself in a "V" between two trees. There was no sign of the deer being hit. It just ran at the sound of the shot. The autopsy showed the bullet pulped the lungs and cut the heart free of all the major blood vessels at the top of the heart. I would have thought this kind of destruction would have brought about hydrostatic shock. The deer was dead the instant the bullet hit. The instinct for animals to run is stronger than hydrostatic shock. Just my two cents. Kent |
Rather than type out a whole lot, I'll just cut and paste something I agree with I found on the 'net: civic.bev.net/shawnee/digress.html Proponents of the "hydrostatic shock" theory usually argue that animals are composed largely of water, and therefore a bullet causes a "shock wave" to be set up in them, which causes displacement of organs, and rupture of tissues. Their belief in this concept is bolstered by the spectacular splashes that expanding bullets make when fired into plastic milk jugs filled with water: they imagine that something of the same thing happens in an animal body. They are wrong. First, animals aren't jugs of water, and don't resemble jugs of water in the least. Animals don't have uniform internal density, and the response of muscle to a bullet is very different than that of, say, the bones or the lungs. At the microscopic level, animals are actually very compartmentalized, and there is almost no "free" water (or any other liquid) to constitute a homogeneous medium in which a "shock wave" can be propagated for more than few millimeters. About the only places where large quantities of fluids are found sloshing around are in the spleen and liver, both of which contain sizeable volumes of "loose" blood. Second, it has been demonstrated quite conclusively that most body tissues are very tolerant of momentary deformation and quite resilient. Unless a bullet physically cuts a blood vessel or nerve, little more than localized damage is done by its passage. It is true that in passing through, a bullet does form a so-called "temporary wound cavity" of considerable size, which lasts for milliseconds. Inside this volume a "shock wave" does form, and it even displaces some organs. But the effect of the temporary wound cavity is small, and most tissues and organs resist this very brief deformation. There is certainly no possibility--as you will frequently be told by ignorant gunshop clerks--that you can "...hit a man in the arm and the shock will travel through the blood to his brain and kill him..." Blood is carried in blood vessels, and those vessels are tough. Anyone who has dissected a freshly-dead animal will testify to the strength of an artery: it takes a good deal of force to rupture one, and physical displacement for a few milliseconds isn't enough. It's perfectly possible to displace an artery by several inches permanently with no loss of function. To do significant damage the artery has actually to be hit by the bullet, preferably by the sharp edges of the expanded outer jacket, which will cut it. Furthermore, there is no way the "shock wave" could "travel through the blood" because the design of the system is such that a) it permits only one-way flow; and 2) it dampens pressure oscillations of considerable magnitude. Arteries that carry blood to the body are very muscular structures and designed to resist considerable heads of pressure lest they burst. And as they get smaller and smaller, ramifying to all the organs, the resistance to flow increases greatly. Even if you were to set up a significant "shock wave" locally, it wouldn't get very far in the system before the increasing resistance to its passage would dampen it out completely. The True Believers in the "hydrostatic shock" myth often point to the messy soup found inside the chest of deer hit in the lungs as "proof" they are right. But they are really pointing to a major hole in their argument. There isn't any "free" blood in the chest of any mammal: like blood elsewhere, it's in blood vessels. The lungs are a sort of enormous capillary bed, with millions of small blood vessels lying between the gas-exchange surfaces. Most of the volume of the chest is air. The vast quantities of blood found in the chest cavity of a lung-shot animal weren't there when the shot was fired. The free blood found in the chest after a shooting got there because the bullet damaged the blood vessels running through the area. An expanding bullet does a fearful amount of damage to the extremely delicate tissue of the lungs, but this region also includes major blood vessels (the aorta and pulmonary artery, to name two) which are usually damaged as well. These pour enormous quantities of blood into the thoracic cavity when they're ruptured. Contraction of the body musculature and the pumping of the heart (if it too isn't hit) will assure this. The blood in the chest cavity is the result of the damage, not the cause of it, and the "shock wave" isn't propagated through it at all. |
What?? 7.62 nato point blank is near 3000 Foot Pounds of Energy ... the guy didn't even step backwards? Ryan |
Yes i Know =( pittiful aint it.Im crying right now ...My dad is also pissed he didnt get a chance to buy ar-15's with a detachable mag |
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The video you speak of was released by www.secondchance.com, one of the first manufacturers of practical body armor, and one of the largest manufacturers currently. The owner/founder, Richard Davis, put on one of his vests and allowed someone to shoot him with a FAL (IIRC, but it was definitely a .308 Winchester) from a few feet away. And he was STANDING ON ONE FOOT when he was shot. Not only was he not killed, he wasn't even knocked down. Of course, he had the advantage of knowing he was going to be shot, but you get the idea. If it isn't big enough to knock down the shooter, it isn't going to knock down the shootee unless it's just knocking him off-balance or severing a major support structure in the body. But, yes, I know, you've SEEN it happen (in the movies, on TV, etc.) so it MUST be true...   -Troy |
This goes back to my original statement: The energy required to accelerate the bullet is the same required to decelerate the bullet (assuming no energy loss during flight of the bullet) . Assuming the front panel of the vest weighed 9 pounds you could approximate what Rich Davis felt by shooting the FAL from your chest instead of your shoulder (maybe add a phone book between the FAL and your chest to approximate the trauma plate I would assume was in that vest). You must keep in mind the 3000 foot pounds of energy is not the same as a 3000 pound force. It can be described as the energy created by dropping 3000 pounds 1 foot, but it is not the same as having a 3000 pound weight dropped on you from 1 foot. In the last example you would be crushed. The 3000 pounds would continue to apply force to your body for a very long time period. In the case of a bullet the energy is delivered in a few milliseconds. The actual force (push) applied is very small. Making some assumptions I calculate in the neighborhood of a couple hundred pounds depending on the rate of deceleration of the bullet, but applied for just a few milliseconds (F=MA: Acceleration is very high but the mass is very low) . Then there is the targets inertia holding it in place. Conservation of momentum law says: MV (first body)= MV (second body) where M=mass V=velocity. Using my own body (180 lbs) as an example and a 180 gr bullet at 2800fps the resulting velocity of my body would be too low to measure easily (.4 fps). So science says you won't fall over from the force of the bullet hitting you. Must be that tissue damage thing coming up again. Kent |
I agree with that too. I'm referring to, what appears to be, an instantaneous loss of conscienceness upon impact of the round. I "dropped like a sack of potatoes off a flat bed truck" more than one Michigan white tail with a shot to the neck or front shoulder, with a .30.30 no less. I have since started using the double lung shot like one would use in bow hunting. Wastes less meat. Even with a 7mm Mag they take off on a 100 yard death run. Fortunately the blood trail is easy to follow. |
I agree with your observations. Mine have been similar. I believe (non-scientific statement here) when you hit the bones close to the spine it stuns them. We need a professional hunter or someone with more experience hunting than I have to weight in on my theory. The two deer I have shot in the spine were instant lights out others I've seen shot in the shoulder or even the pelvis go down at least temporarily. The gang I used to hunt with pushed deer in a manner similar to small game hunting. The deer where almost always running when shot so the shots may not have been the best. We always had enough people in our drives that we never lost a wounded deer. Usually the deer never got out of our sight before they were put down for good. Consequently, I have developed the opinion that if you hit bone in the body the deer falls or at least slows enough to make the second shot easy. The average number of shots into a deer in our case was between two and three. One or two to stop it and one to finish it. Hope I haven't bored you with my theory. BTW what area of MI do you hunt in Halfcocked? Kent |
The Human (and other animal) bodies are run by electrical nerve impulses - bullets tend to play havoc with this (as well as major tissue damage) , especially if the main conduit for these (the spine) is impacted. |
So the question of the day in my mind is: Will a hit in the bones connected to the spine (i.e. shoulder, pelvis, or ribs) disrupt the nerve impulses at least temporarily? |
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I don't know - I would say maybe :) - try asking this over on Tactical Forums - Terminal Effects 64.177.53.248/cgi-bin/tacticalubb/forumdisplay.cgi?action=topics&forum=The+Terminal+Effects+Forum&number=78&DaysPrune=10&LastLogin= The mods over there are on the cutting edge. |
Unlikely. Ever break a rib? Were your nerve impluses temporarily interrupted? |
[ARCHIVED THREAD] - quick newbie question (Page 1 of 2)
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