Bullet Penetration Question
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Sectional densities:
8mm 200 grain.... .274
8mm 220 grain.... .301
.411 300 grain.... .254 oh,oh.
conclusion?
Flat point solids have been proven to penetrate better in suitable test media. How much of that applies to softs in wood, I wouldn't venture a guess.
8mm 200 grain.... .274
8mm 220 grain.... .301
.411 300 grain.... .254 oh,oh.
conclusion?
Flat point solids have been proven to penetrate better in suitable test media. How much of that applies to softs in wood, I wouldn't venture a guess.
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Lets consider two bullets, a spitzer and a flat point, both in nonexpanding flat base construction that impact an aquous target at super sonic velocity. As the spitzer passes through the target medium, it is in contact with the medium along it's entire length and this friction begins to slow it down very quickly. The flat nose bullet produces a shock wave at the bow, and the bullet never actually contacts the target medium until it's velocity becomes subsonic.
Another problem the nonexpanding spitzer has is that it's center of gravity is at the base of the bullet, so the instant it comes in contact with the target medium it will attempt to swap ends. When the bullet is midway through it's turn, there is a great risk of it breaking in two, resulting in a loss of momentum due to the loss of weight and therefore less penetration resulting in a shallower if wider wound cavity. The flat nose bullet by comparison will produce straight line penetration, provided it is constructed with parallel sides.
Now let's consider the wound cavity on game produced by two soft point bullets; one being a spitzer and the other a flat point. Once the bullets have fully expanded, both have the advantages of the flat nose bullet as described above, and provided that the construction of the bullets is strong enough to retain their mass, the large frontal area ensures that penetration will be straight and deep. The advantage of the flat nose bullet on game however is that the entrance wound on a game animal from a spitzer might be a pinhole that will quickly close up and produce a minimal blood trail, where the flat point bullet creates a large entry wound that will bleed freely.
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It seems a bullet with a large metplat often is a good penetrator even at slower velocities. Many of the old British designs for dangerous African game used fairly large flat areas at the front and were not exceptionally high velocity. Some of the bullets used by long range black powder cartridge shooters are very pointy but would not be my first choice for hunting. It is almost as though the flat metplat "cuts" or "punches" out a hole through which the bullet can pass. If the bullet is of sufficient diameter then it will do enough damage with only minimal expansion. When a bullet expands there is a lot of the energy it was carrying used up in this reshaping and of course it needs even more energy to keep driving the now expanded diameter forward .I believe this is especially true when shooting into a solid like wood.
Bullet shape has very little to with penetration with modern bullets and everything to do with how fast they expand. Second, if anyone thinks a bullet travels nose first through an animal or test medium, they are mistaken. The second a bullet starts to expand, it begins to tumble. No bullet can expand in a perfectly uniform manner and one edge will drag more than the other causing the bullet to tumble. Certainly sectional density plays a role when comparing bullets of identical construction but other than that, it has no bearing either. Most of the thoughts we have about bullet penetration are outdated and do not apply to modern bullet construction. Shoot a TSX into test medium and tell me a flat nose bullet penetrates better.......not a chance.
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I see boomer, you are talking about solids.
Though just to add... sometimes in very hard material, like wood, a round nose solid is supposed to out do a flat nose sometimes, just something I read.
I have shot FMJ spire points out of a 308 at stuff (not game) and ya, they sometimes tumble all over the place and generaly act funny.....wich reminds me I have some 308 surplus ammo I forgot about hummmm
Though just to add... sometimes in very hard material, like wood, a round nose solid is supposed to out do a flat nose sometimes, just something I read.
I have shot FMJ spire points out of a 308 at stuff (not game) and ya, they sometimes tumble all over the place and generaly act funny.....wich reminds me I have some 308 surplus ammo I forgot about hummmm
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Sheephunter -
None of the bullets above tumbled. A bullet may impact in a yaw but this is a far cry from one that tumbles upon impact. Expansion of the nose of the bullet moves the center of gravity to the nose, so it would be all but impossible to tumble. The bullet's shape and construction combined with it's momentum has everything to do with how well a bullet penetrates. Sectional density is meaningless in any discussion of the impact ballistics of soft points.
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None of the bullets above tumbled. A bullet may impact in a yaw but this is a far cry from one that tumbles upon impact. Expansion of the nose of the bullet moves the center of gravity to the nose, so it would be all but impossible to tumble. The bullet's shape and construction combined with it's momentum has everything to do with how well a bullet penetrates.
Having shot hundreds of bullets into test mediums, I can assure you that they do indeed tumble. As a bullet expands, its centre of gravity actually shifts to the base of the bullet and the base quite literally tumbles forward with the base becoming the leading face in many cases. This likely does not occur as dramatically with solids but with controlled expansion bullets like 99.9999% of North American hunters use, it is indeed a fact. The more rapid the expansion, the more dramatic the tumbling. Obviously this tumbling action would be mitigated in wood but in a true test medium or animal flesh it occurs. I was surprised the first time it was proven to me as well but I'm now a believer.
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Sheep hunter, why is it then that nearly all (most) of the bullets I have recovered from wet or dry phone books, clay, trees, rice, are found with the bullet facing forwards. Most of the ones I have found that were facing backwards or askew had lost the jacket, or were expanded to the point that the bullet was wider than it was long.
I do agree that on soft points the shape is a factor on how easily or quickly they expand. That is a no brain er, round nose or flat point, especially with lots of exposed lead and cuts in the jacket are manufactured specifically for low velocity cartridges.
If you are who I think you are I have a signed copy of your book, title initials W.A.T.W. ???
I do agree that on soft points the shape is a factor on how easily or quickly they expand. That is a no brain er, round nose or flat point, especially with lots of exposed lead and cuts in the jacket are manufactured specifically for low velocity cartridges.
If you are who I think you are I have a signed copy of your book, title initials W.A.T.W. ???
Sheephunter,
There were no TSX bullets is this informal "test", and all three were lead/copper construction.One was bonded, granted. Bullets that I find under hides always seem to be facing facing the right way.Exit holes in hide are usually round and seldom keyholed. Penetration tests have proven that bullets can usually penetrate without tumbling, as demonstrated by putting baffles inside. High speed photograghy shows bullets going through ballistic gel without tumbling. Sometimes they flip at the end.
It sounds like you been reading Alf over at AR again? The guy doesn't let reality get in the way of theory, or his readings of about spire pointed military FMJ. It's really quite funny. Sporting bullets can tumble, sure. It's far from normal.
There were no TSX bullets is this informal "test", and all three were lead/copper construction.One was bonded, granted. Bullets that I find under hides always seem to be facing facing the right way.Exit holes in hide are usually round and seldom keyholed. Penetration tests have proven that bullets can usually penetrate without tumbling, as demonstrated by putting baffles inside. High speed photograghy shows bullets going through ballistic gel without tumbling. Sometimes they flip at the end.
It sounds like you been reading Alf over at AR again? The guy doesn't let reality get in the way of theory, or his readings of about spire pointed military FMJ. It's really quite funny. Sporting bullets can tumble, sure. It's far from normal.
Not reading anything....just going on personal experience. This photo demonstrates typical performance in ballistic gel. Notice the size of the wound channel at penetration where the most violent tumbling occured. Also notice how bullet came to rest. This was not an anomoly but a very typical test.
Rupublic.....most of the mediums you describe are great for stopping a bullets but a poor medium if you truly want to see what a bullet does in flesh.
Yes, that is indeed me.
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Thought so, that is a good book!
sheephunter the large size of the entrance hole is due to the bullet expansion on impact. Then once that expansion has occurred the bullet continues forward and the wound channel remains that size unless something else is struck like a bone that might cause further expansion or deflection.
Btw where do you get the ballistic gelatin? What's that stuff cost?
Btw where do you get the ballistic gelatin? What's that stuff cost?
I've recovered bullets from animals (the best test medium) and I've found them to have held together, turned to shrapnel and everythign in between.
But I can't say that many of them have tumbled.
All the ones that hold together (X bulet, TSX, Partition, Accubond) have been recovered pointing in the correct direction.
I've also seen the high speed filming of bullets in ballistic gelatin that show bullets going forward, not tumbling.
I'd like to see where sheephunter came to his conclusions that bullets almost always tumble. The photo of the ballistic gelatin really doesn't tell us much. It's difficult to even see the bullet.
But I can't say that many of them have tumbled.
All the ones that hold together (X bulet, TSX, Partition, Accubond) have been recovered pointing in the correct direction.
I've also seen the high speed filming of bullets in ballistic gelatin that show bullets going forward, not tumbling.
I'd like to see where sheephunter came to his conclusions that bullets almost always tumble. The photo of the ballistic gelatin really doesn't tell us much. It's difficult to even see the bullet.
Tumbling is perhaps not the correct word in the fact that most people think that tumbling indicates that the bullet actually spins from front to back rapidly which of course it does not. More often than not, it does a slow roll so it is moving through the gel canted or even on it's side. Unfortunately, even with balistic gel, the gel quickly overcomes the tumbling action and contains the bullet. The slower the velocity, the less tumbling action just for the reason that the gel can contain the bullet. In an animal where the are huge air voids, bone and changes in muscle and organ density, the bullets undoutedly has more chance to roll or tumble unfettered. The path of the bullet remain fairly straight but there is no way it can travel nose fiirst the entire length of the would channel.
PermaGel is likely the best source of consumer ballistic gel.
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I too have recovered bullets that have tumbled. They have been without exception FMJ's and when they have tumbled they have been bent into a banana shape. Soft point bullets that perform properly do not tumble.
There is probably a good argument to made that once expanded and while the bullet remains super sonic, it is untouched by animal tissue other than bone, due to the shock wave that moves ahead of the large expanded nose. If this proved to be true, it would also prevent the bullet from tumbling.
By the way, the bullet in your pic appears to be at rest nose on after making straight line penetration. Straight line penetration is not possible if the bullets acts as you describe.
There is probably a good argument to made that once expanded and while the bullet remains super sonic, it is untouched by animal tissue other than bone, due to the shock wave that moves ahead of the large expanded nose. If this proved to be true, it would also prevent the bullet from tumbling.
By the way, the bullet in your pic appears to be at rest nose on after making straight line penetration. Straight line penetration is not possible if the bullets acts as you describe.
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Most definitely the great damage at entry is caused by the initial shock and high speed photography graphically illustrates how violent it is but as you track the wound channel it easy to see that the bullet did not travel nose first for the entire length. The best way to see this is to split the gel and examine the channel but high speed video shows it very well too.
Gatehouse, I too have recovered many bullets over the years from animals and I'd say the vast majority recovered in muscle have not been point forward. There's little doubt that when the bullet hits the far side hide that it's going to be forced into a nose forward position by the elasticity of the hide but keep an eye on the ones that come out of muscle and not hung up on hide and you'll be amazed where they are pointing.
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