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Posted: 12/20/2003 2:04:28 PM EDT
[#1]
No flames from me, I think you're right on target!
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Posted: 12/20/2003 2:11:10 PM EDT
[#2]
I think the two resident ammo gurus did some testing on 100 grain OTM rounds, and posted their findings on this board.
If memory serves, the 100 grain OTM had a much lower fragmentation threshold than 55 grain M193 ball. Makes sense to me, considering how long a 100 grain .223 would have to be; that's an awful lot of surface area for outside forces to act upon. |
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Posted: 12/20/2003 2:59:42 PM EDT
[#3]
Well, to a point, you are correct. Short barrels severely hurt the 5.56's performance.
However, you also need to consider that heavier (longer) bullets fragment at much lower velocities AND retain their velocity for a longer distance than lighter bullets. The 75/77gr loads will fragment down to about 2100fps. The 100gr is essentially dead. |
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Posted: 12/20/2003 4:04:14 PM EDT
[#4]
This is covered in the [url]www.ammo-oracle.com[/url], but aside from velocity, one of the other HUGE factors for bullet fragmentation is BULLET CONSTRUCTION.
These heavy match bullets have thin jackets, and the bullets themselves are longer, which means that they encounter more resistance and friction when the bullet yaws. The result of this is that these bullets will still fragment at much lower velocities than either M193 or M855 bullets will. So, even though these bullets have a lower initial velocity, they retain their velocity better (higher BC) and will have longer ranges until they reach their velocity floor for fragmentation. Here's an example, with numbers made up off the top of my head: Let's say an 11.5" barreled AR has a muzzle velocity of 2780 fps with M193, and 2670 with M855 (these are pretty close to actual specs). You can see that fragmentation range is only going to be a few feet with M193, and zero for M855, assuming 2700 fps is the velocity floor. The same rifle will fire 77gr ammo at, say, 2400 fps, which of course is slower than the above loads, BUT the velocity floor for fragmentation is around 2200 fps. This gun would probably give reliable fragmentation to 60-90 yards with this ammo. See the advantage now? Ballistics isn't always as simple as it appears, as so many factors affect the outcome. This is why many generalizations are false, and why you can't make generalizations from only a small number of datapoints. That's what most people try to do, and that's why few people really know the truth about how and why their ammo performs. -Troy |
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Posted: 12/21/2003 12:26:09 AM EDT
[#5]
What I don't understand about Fackler's article is this: it always mention a projectile entering a solid muscle mass such as the tigh. What will happen, then, if the 5.56mm projectile penetrated a less substantial organ such as the lung? Will the projectile still fragment?
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Posted: 12/21/2003 3:30:44 AM EDT
[#6]
To my understanding the bullet will still fragment but deeper in the tissue. Say instead of fragmenting at 3" it will do it at 5". This will give you more penetration though.
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Posted: 12/21/2003 6:03:08 AM EDT
[#7]
The wounding effects of M193 Ball were well known in Vietnam, but it wasn't until ~1988, long after the War that any one had a clue what caused these wounds. We thought (and taught) that the bullet "tumbling" in the target is what caused the damage. There was no inkling of the fragmentation and shredding of the temporary cavity.
This was discovered by scientific testing into calibrated 10% ballistic gelatin which is well documented to mirror the [i]average[/i] construction of the human body. Key word is average. The average M193 Ball wound in the human body will look exactly like the wound in the ballistic gelatin. Individual wounds can be better or worse. What we get is [i]wounding potential[/i] not assurred wounding. The minimum velocity for M193 Ball to reliabily fragment is ~2700 fps; below ~2500 fps the bullet is unlikely to fragment. New bullets are being designed to fragment at lower velocities which, depending on their muzzle velocities, may result in reliable fragmentation effect at longer shooting distances. This is the first attempt to create a bullet based on scientific wounding criteria. There was no intent to create these wounds when either the AR15/M16 rifle was designed, nor when 5.56mm M103 Ball was designed. It's pure accident. The cause wasn't known for a good 25 years after the rifle and cartridge were releases. Using the since discredited "kenetic energy" standard they Army thought that sixty (60) lb-ft2 was what was necessary to cause a "disabling wound" and M193 Ball is way above that criteria. -- Chuck |
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Posted: 12/21/2003 6:58:48 AM EDT
[#8]
Knowledge is really cool shit.
Thanks, guys. The real good news in all this is that we seem to have gotten by the Hague Convention silliness (which we never even signed on to) and are getting on with the business of designing military bullets to meet their clear and obvious purpose: to do as much damage to the enemy as possible. Brouhaha: Can you point out to me the exact thread in AO that addresses these lower fragmentation velocities so that I can study on this a little more? Thanks, all. SD |
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Posted: 12/21/2003 7:17:36 AM EDT
[#9]
The 100gr is essentially dead. What is up here? What happened? |
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Posted: 12/21/2003 8:43:35 AM EDT
[#10]
Quoted: Brouhaha: Can you point out to me the exact thread in AO that addresses these lower fragmentation velocities so that I can study on this a little more? [url]http://www.ammo-oracle.com/#velocity[/url] Heavy Metal, Honestly, I don't know all the reasoning. But, I'm sure it has to do with the bullet's rainbow trajectory coupled with the fact that the 75/77gr bullets have similar terminal performance at a better price (they were off-the-shelf bullets). |
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Posted: 12/21/2003 7:05:19 PM EDT
[#11]
Actually, all of the bullets that are being used in the current "improved fragmentation" loads were off-the-shelf designs that were designed with other goals in mind.
For example, all of the open-tip match bullets were designed to shoot accurately at long distances, with NO thought as to wounding capability. It just turns out that the things that make good long-range match bullets in this caliber also help ensure fragmentation at lower velocities. These bullets have thin, consistant bullet jackets and an elongated profile, both factors that aid fragmentation as well as long-range accuracy. But bullet manufacturers ARE using this data to work on new designs, or modifications to existing designs, that should provide all of us with better performance in the future. -Troy |
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Posted: 12/21/2003 7:16:34 PM EDT
[#12]
Quoted: What I don't understand about Fackler's article is this: it always mention a projectile entering a solid muscle mass such as the tigh. What will happen, then, if the 5.56mm projectile penetrated a less substantial organ such as the lung? Will the projectile still fragment? I hope you're not thinking of the lung as a hollow balloon. That's not the way it's constructed. Regardess of which - the bullet yaws quickly upon entering ANY substance in the human body. The density difference between air and tissue (of any kind) is huge, compared to slight differences in density between one type of tissue and another. |
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Posted: 12/22/2003 8:03:34 AM EDT
[#13]
Quoted: For example, all of the open-tip match bullets were designed to shoot accurately at long distances, with NO thought as to wounding capability. -Troy Question: Were heavy OTM bullets completely designed independantly, or did they rely on technology previously used to construct the lighter varminting Hollow points? Seems like I remember hearing this long ago. That the construction of the Hollowpoints also led to a more uniform and accurate bullet which fragmented rapidly, and that the heavy match bullets were made the same way for accuracy, but the hollowpoint was not designed to expand (only concern with the accuarcy benefits of the HP construction). But in the end these match bullet did prove to fragment not because of the hollow tip, but because of other factors(jacket thickness, etc) that where design traits of the light hollowpoints. Is this correct? |
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Posted: 12/22/2003 12:13:19 PM EDT
[#14]
Quoted: Quoted: What I don't understand about Fackler's article is this: it always mention a projectile entering a solid muscle mass such as the tigh. What will happen, then, if the 5.56mm projectile penetrated a less substantial organ such as the lung? Will the projectile still fragment? I hope you're not thinking of the lung as a hollow balloon. That's not the way it's constructed. Regardess of which - the bullet yaws quickly upon entering ANY substance in the human body. The density difference between air and tissue (of any kind) is huge, compared to slight differences in density between one type of tissue and another. Make sense. Thanks, Zhukov! |
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Posted: 12/22/2003 12:50:18 PM EDT
[#15]
Quoted: Quoted: For example, all of the open-tip match bullets were designed to shoot accurately at long distances, with NO thought as to wounding capability. -Troy Question: Were heavy OTM bullets completely designed independantly, or did they rely on technology previously used to construct the lighter varminting Hollow points? Seems like I remember hearing this long ago. That the construction of the Hollowpoints also led to a more uniform and accurate bullet which fragmented rapidly, and that the heavy match bullets were made the same way for accuracy, but the hollowpoint was not designed to expand (only concern with the accuarcy benefits of the HP construction). But in the end these match bullet did prove to fragment not because of the hollow tip, but because of other factors(jacket thickness, etc) that where design traits of the light hollowpoints. Is this correct? No this is 100% wrong. Conventional hollow point have exposed bases. They are desigend to expand and the hollop tip is there specifically to allow it to fragment. It does NOT make it more accurate. It makes it LESS accurate. Now when you construct a bullet you have two choices. You can put the jacket on from the top and leave the base exposed (FMJ design) or put it on from the bottom and leave the tip exposed. This is the only way to get consistant jacketing. Since the number one thing that determines accuracy of a bullet is how the gas flows at the base of the bullet as it leaves the barrel you want it covered in copper and consistant as possible. You dont want exposed lead there to change the rear of the bullet as it moves down the bore with hot gas behind it. The tip hurts its aerodynamics but accuracy is the concern with match ammo. Also a thin jacket is easier to keep consistant. So the small hole at the tip is a simple artifact of how the bullet is constructed to get a consistant base on the bullet. This is the opposite of a conventional hollow point where the base is exposed and the tip is opened to get expansion. I might have a nuance wrong here or there and this is certainly over simplified but you should get the idea. |
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Posted: 12/22/2003 1:14:37 PM EDT
[#16]
Quoted: Question: Were heavy OTM bullets completely designed independantly, or did they rely on technology previously used to construct the lighter varminting Hollow points? They were completely designed independantly. The only reason these bullets have a hollow point is because, for accuracy reasons, the BASE of the bullet needs to be jacketed. Bullet jackets are like a cup, or, actually, more like the shape of a test-tube. The closed end will either create the nose of the bullet, as with FMJ designs, or the base of the bullet, like most hollow-point and match bullets. With the match bullets, the nose can't be closed completely, and it doesn't really need to be. Nothing about the OTM bullets was purposely designed to cause fragmentation, and in fact they are designed just like other OTM bullets that [b]don't[/b] fragment, due to length and/or size. It just so happens that THESE bullets in THIS caliber at THESE velocities fragment well. -Troy |
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Posted: 12/22/2003 4:32:39 PM EDT
[#17]
No this is 100% wrong. Conventional hollow point have exposed bases. They are desigend to expand and the hollop tip is there specifically to allow it to fragment. It does NOT make it more accurate. It makes it LESS accurate. Now when you construct a bullet you have two choices. You can put the jacket on from the top and leave the base exposed (FMJ design) or put it on from the bottom and leave the tip exposed. This is the only way to get consistant jacketing. Since the number one thing that determines accuracy of a bullet is how the gas flows at the base of the bullet as it leaves the barrel you want it covered in copper and consistant as possible. You dont want exposed lead there to change the rear of the bullet as it moves down the bore with hot gas behind it. The tip hurts its aerodynamics but accuracy is the concern with match ammo. Also a thin jacket is easier to keep consistant. So the small hole at the tip is a simple artifact of how the bullet is constructed to get a consistant base on the bullet. This is the opposite of a conventional hollow point where the base is exposed and the tip is opened to get expansion. I might have a nuance wrong here or there and this is certainly over simplified but you should get the idea. Devl, Don't confuse a Hollow point with an Open tip. A hollow point is designed for terminal performance while an open tip is designed for external performance. An open tip is more accurate because it creates a pocket of air in front of it resulting in less drag. Before I got out of the Corps, we started using the new open tip ammo in our M40s. It was holding 1/2 minute or better and was much flatter shooting that the old Match King stuff. That is significant since the old ammo was 168 gr and the open tip is 175. What is noteworthy about .223 hollow points is that many of them are actually just open tips with cuts in the jacket to improve expansion. At short ranges, they perform externally just like an open tip, yet als perform internally like a hollow point, best of both worlds. |
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Posted: 12/22/2003 5:53:57 PM EDT
[#18]
Quoted: An open tip is more accurate because it creates a pocket of air in front of it resulting in less drag. Umm... no. The hollow tip has NOTHING to do with anything, other than the bullet manufacturers are unable to close the nose of the bullet in a consistant way, so they're left open. The reason these rounds are more accurate is because the jacket and especially the bullet base is extremely uniform. The reason they fly well long-distances is because they have a low coefficient of drag (or "ballistic coefficient [BC]). The open tip does not contribute to this, BTW. The improved BC comes from the elongated profile of the bullet. -Troy |
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Posted: 12/22/2003 5:54:24 PM EDT
[#19]
Im not confusing anything. If they could get a uniform jacket with no hole in the tip during manufacture they would. It would increase the ballistic coefficent and help practical accuracy. THats why the AMAX exists... to increase the BC of the match bullets. Like I said conventional hollow points are not similar to open tips at all. Many conventional hollow points have exposed bases (but not all). Also your mistaken with the OTM having the tip be the source of accuracy. Its the BASE of the bullet where it gets its accuracy from not the tip. The Game King is an accurate soft point load but the bullet nose can be mashed and harm accuracy during loading becasue of the soft lead. In fact a flat base bullet is better for accuracy than a boat tail design. However the boat tail helps practical accuracy by decreasing drag. The OTM designs have air in the tips. Most hollow point designs have lead all the way up toward the tips. By having a flat lead tip covered with the copper jacket above it its easier to attain consistant accuracy and a better BC.
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Posted: 12/23/2003 3:22:16 PM EDT
[#20]
Many conventional hollow points have exposed bases (but not all). Most conventional hollowpoints have covered bases. The only exception seems to be the FMJ with the tip ground off the russians try to pass off as hollowpoint rounds. |
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Posted: 12/23/2003 6:04:41 PM EDT
[#21]
Quoted: Many conventional hollow points have exposed bases (but not all). I have been reloading for 20 years and I have never, ever seen a HP bullet with an exposed lead base. Please tell me which American brand is like this? It is considered unsafe to SP a FMJ bullet by cutting the tip, so that the bullet is open on both ends. The core may shoot ouot and leave the jacket in the bore, causing a KaBoom next shot. Larry |
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