It is a common opinion that the higher is the velocity of a bullet and the better it will penetrate.

From my practical experience I found that, all others factors being equal, the faster bullet gives me a better trajectory but absolutely no better penetration, particularly at short range.

In addition I never experienced bullet failures at the slow velocities of the 9.3 x 62 and 458 WM, but I witnessed plenty on faster calibers

Any comment?

You are totally dependant on the integrity of the bullet in either case. The better made the bullet(the expensive ones), the better it will hold up under the velocity envelope you'll put it through. You should ask that Old Ideeho cowboy about solids and penetration.

And others have pointed out that the faster speed bullets may be yawing more in the first 20 yards of flight, hence be unstable until they "go to sleep" ...

The faster twist barrels might give better penetration at all ranges versus the slower twist.

But, at 25 yards or more, all else being equal, the faster bullet will penetrate deeper, if it is a nondeforming tough solid, and the FP or FN solid is better than the round nose, when it comes to staying on course and at cutting a bigger wound channel.

And probably any sectional density over 0.300 is not needed with a tough solid FP bullet. Just drive the .3 SD bullet faster and it will work better.

Actually higher velocity usually means less penetration with expanding bullets. Some of the best penetration comes with non-expanding handgun bullets traveling 1200 or so fps.

quote:

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Originally posted by M16:
Actually higher velocity usually means less penetration with expanding bullets. Some of the best penetration comes with non-expanding handgun bullets traveling 1200 or so fps.

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Some soft nose bullets explode on the surface and leave shallow crater wounds, and high velocity and frangible bullet are the culprits, of course.

No handgun bullet at 1200 fps will out penetrate a Flat Point monometal copper solid rifle bullet of 0.3 SD at 2400 fps, of course, in any medium or game.

That same super-penetrator rifle bullet will work better at 2700 fps than at 2400 fps, but it is diminishing returns at some point, and a recoil trade-off price to pay.

It all depends upon who's leading the discussion, and whose pet theories are on the line.

If you'd compare someone's pet .45-70 with special hard-cast bullets to the .458 Win. Mag., then the answer is, "slower penetrates better."

If you'd compare that same obsolete .458 Win. Mag. to another guy's .450 Dakota, then the answer is, "faster penetrates better".

AD

There are documented stories of the 7 X 57 out penetrating the 7MM Rem Mag on elk hunts.(Elmer Keith)

I personally witnessed the .44 special shooting carp in rivers deeper than the same gun with .44 mags.....240 Gr HP in both.

Then one day I discovered that the .22 Long Rifle 40 grain bullet would outpenetrate the same cartridge with a hollow point....DUH!!!

It's very clear to me that the faster rounds with EXPANDING bullets expand faster and as a result may not penetrate as deep but do an immense amount of damage in the distence they did penetrate.

All this is not any news to anyone....John Nosler knew this a zillion years ago when he developed the partician bullet. Solids are the result of the question of how to penetrate deeper on the very largest critters.

I truly believe that what we have today is the knowledge that there's a maximum benefit of bullet style, shape, and velocity for each kind of game and added to that is the developement of controlled expansion bullets such as the TBBC and Northforks and A-Frames etc.

I wish it was simple and of course it really is.....just read the accounts of a lot of folks that have been there and done that and learn from them. How many times does "old Ray" have to tell us about the bullet to use and the velocity to drive it at?

BTW, tomorrow, someone will comeup with a new cartridge/bullet combination and things will change.....trust me.....someone will test it and write about it.....

quote:

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Originally posted by Andrea Sandri-Boriani:
From my practical experience I found that, all others factors being equal, the faster bullet gives me a better trajectory but absolutely no better penetration, particularly at short range.

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Unfortunately I do not have it at hand, so I'm going solely on memory, but I remember an article some years ago in one of the magazines where penetration tests were done using various bullets in a .308, a .30-06, and a .300 Winchester mag -- the same bullets were loaded to typical velocities in each of those three cartridges. As I recall, all of the bullets were standard soft point ones (i.e. no solids or FMC ones) from Hornady, Sierra, and Speer, and possibly Nosler Partitions.

The results from those tests, as I recall them, were that the lower velocity loads (from the .308) penetrated more than the higher velocity ones (from the .30-06 and .300 Winchester), and the ones from the middle velocity (from the .30-06) penetrated less than the ones from the lower velocity but more than those from the highest velocity. In other words, penetration was inversely proportional to velocity.

Obviously, however, there would have to be a lower end cutoff to that principle, as a bullet at zero velocity would not penetrate at all, and one at some very low velocity, say 500 f.p.s. would penetrate only a little. So it would be interesting to know where that principle (assuming that it is indeed a true principle) -- lower velocity penetrates better than higher velocity -- begins to take effect.

Some bullets are designed to penetrate better at certain velocities. It is true that you are probably more dependent on the construction of the bullet than most would like to admit. But if that were not true then why go thru the metallurgical exercises of bonding jackets to cores and plasticizing bronze?

Velocity is just one parameter of the terminal ballistics equation. Mass of the bullet and Kinetic energy are some others. Bullet construction determines how much energy contributes to the frangibility of the bullet and how much energy is available for penetration. That being said slower moving bullets are often heavier and of sturdier construction, thus leaving more energy available for penetration. But this does not mean a higher velocity robustly constructed bullet cannot out penetrate it.

Yep, softs and solids are tomato versus apple in velocity/penetration comparisons.

Even a round nose solid versus a flat nose solid are banana versus apple in velocity/penetration comparison.

Apples and oranges.

quote:

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I remember an article some years ago in one of the magazines where penetration tests were done using various bullets in a .308, a .30-06, and a .300 Winchester mag...

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I should add -- what nobody here needs to be told -- that there are several problems with any penetration tests that make those tests, at best, only approximations of what can be expected in actual hunting situations.

(1) No test medium -- whether it is plywood boards, water-filled plastic bottles, ballistic gelatin, water-soaked newspaper or phone books, or whatever -- has the actual complexity of an animal's body. The animal's body will have a combination of skin or hide, muscle, bone, water-filled sacs, and so on, and will vary even from one animal to another of the same size and the same species. When you think about the differing bodily construction of animals of different species, the problem becomes even more complex.

(2) Any shots into test media, if the test is done properly, will be consistent from shot to shot and bullet to bullet. The test media will not change from one test to another, and the shots will be presented to the test media at the same angle. But no two animals, nor any two shots on animals, are ever exactly the same. The animals will differ from animal to animal -- both in bodily construction of the animal and in the disposition of the animal -- and the shots will differ in terms of angle, point of impact, etc.

Let's see if I have this right. A bullet going 0 fps will penetrate a buffalo from stem to stern.

From my limited experience, the greater the Penetration Index, the greater the penetration; and you have to have velocity to get it.

This shows up in the high sectional densities of heavy for caliber bullets in cartridges such as the 7x57, and heavy bullets for the .375 H&H, and for high velocity 416's and 458's.

But that is only part of the story, because you have to have energy (ft-lbs) to back it up.

Comparing penetration, or anything else, for that matter will drive you nuts if different bullet types or different calibers are involved.

Given a particular bullet and calibre, at different speeds as one will have from muzzle to extreme range, penetration will be lowest at high speed close to the muzzle. Penetration will gradually increase as distance increases, until it starts dropping off again when velocity falls off markedly.

The lesser penetration at higher speeds has to do with the higher level of stagnation pressure on the nose of the bullet and not to do with any instability of the bullet still being "awake".

From four to seven calibers in front of the muzzle, speed and gyroscopic stability is fixed. Any precession caused by the bullet leaving the muzzle at an angle is dampened by the gyroscopic stability factor as the bullet goes down range. In a reasonably good rifle, with an acceptably concentric chamber, the angle of attack of the bullet will be less than 0.2 degrees. This is not enough to cause or not cause tumbling or influence penetration.

quote:

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Originally posted by Gerard:
Comparing penetration, or anything else, for that matter will drive you nuts if different bullet types or different calibers are involved.

Given a particular bullet and calibre, at different speeds as one will have from muzzle to extreme range, penetration will be lowest at high speed close to the muzzle. Penetration will gradually increase as distance increases, until it starts dropping off again when velocity falls off markedly.

The lesser penetration at higher speeds has to do with the higher level of stagnation pressure on the nose of the bullet and not to do with any instability of the bullet still being "awake".

From four to seven calibers in front of the muzzle, speed and gyroscopic stability is fixed. Any precession caused by the bullet leaving the muzzle at an angle is dampened by the gyroscopic stability factor as the bullet goes down range. In a reasonably good rifle, with an acceptably concentric chamber, the angle of attack of the bullet will be less than 0.2 degrees. This is not enough to cause or not cause tumbling or influence penetration.

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Gerard,
I knew I shouldn't have believed 500groans on the yaw thing!

Now, stagnation pressure is beyond me, and would seem to mean that too much velocity is bad with any bullet, solid or soft.

Related to slapping water at high speed versus just pushing the open palm slowly down through the surface of the water?

I am an imbecile! As AC claims to be.

Lowest penetration at the muzzle, even beyond that 4 to 7 caliber stabilizing few inches? Is penetration lower at 6" from the muzzle than it is at 100 yards from the muzzle? May be splitting hairs, but this is theoretical.

Some actual data from muzzle to 300 yards with a GSC FN would be very interesting.

Penetration increases as the bullet slows down going down range, and then drops off at some point? What is that point for any specific bullet example?

If you can answer this, it would be worth trying to order bullets from you again, to brave the black hole of RSA post.

Oh no, stagnation pressure!! I wonder if anyone on this forum knows what that means?!!

More nmumbo, njumbo!

quote:

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Oh no, stagnation pressure!! I wonder if anyone on this forum knows what that means?!!

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Stagnation pressure is the pressure at the point of zero air flow velocity in front of the projectile.

It resides directly in front of the projectile point or in the case of a hollow point where the point would naturally be.

quote:

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Originally posted by TheBigGuy:

quote:

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Oh no, stagnation pressure!! I wonder if anyone on this forum knows what that means?!!

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Stagnation pressure is the pressure at the point of zero air flow velocity in front of the projectile.

It resides directly in front of the projectile point or in the case of a hollow point where the point would naturally be.

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Okay, but there is only one stagnation point and it is not where the point would normally be, but how do you calculate it?

But more importantly, what the heck does it have to do with penetration?!!

Will,
Anyone who has read Bullet Penetration by Duncan MacPherson will know the terminology. I am sure many who visit here have and, for those who have not, here is the explanation:

The stagnation pressure on a symmetric body, such as an undeformed bullet, occurs on the forward centerline where the body surface is perpendicular to the direction of travel. Stagnation pressure does not increase at the same rate as speed. Some examples of stagnation pressure at increasing speeds in water are below.

1000 fps 6740 psi
1500 fps 15200 psi
2000 fps 26900 psi
2500 fps 42100 psi
3000 fps 60600 psi

RIP,
Slapping water is in fact the explanation given by MacPherson to clarify the effect of stagnation pressure. As to the cut off points for when penetration increases or decreases, I do not think it can be defined. There are too many variables that influence penetration over and above stagnation pressure. The best I can do is to say, keeping the effect of stagnation pressure in mind, temper the fact with:

1. With FN solids, supercavitation (sorry Will) is highest at high speed and improves penetration.

2. With expanding bullets, expansion and weight loss increase with speed, reducing penetration.

The answer to your question regarding "too much velocity is bad with any bullet, solid or soft" is simply that it depends on the construction and design of the bullet.

With jacketed lead the answer is yes. When stagnation pressure is higher than the tensile strength of the bullet, it breaks and penetration is adversely affected.

With FN solids the answer is no (supercavitation thrives on speed).

With monometallic expanding bullets the answer is maybe. It depends on the design of the forward section of the bullet. I cannot speak for other manufacturers but I design for reliable expansion in an aqeous medium, from 1600 fps. Any HV will expand fully at 1900 to 2000 fps.

The trick for a manufacturer is to offer a bullet with the widest possible window of application in speed. In our case we ensure good terminal performance (penetration) at the highest speed the bullet is likely to be pushed to. If a bullet will get the job done at over 4000fps, things can only improve as it slows down.

With HVs, if the bullet strikes at extreme speed, 12% to 15% of the bullet is shed in the form of the petals. The resulting cylinder shape, resembling an FN, will result in penetration and a single wound channel beyond the size of that caused by a larger diameter mushroomed bullet.

Incidentally, sectional density has little to do with the probable penetration one can expect from a bullet.

I understand that the penetration of a bullet depends mostly on momentum (mass x velocity) and not on kinetic energy (mass x velocity x velocity).

On expanding bullets the higher is the velocity the faster the same bullet will expand, so losing velocity and consequently penetration.

Any expanding bullet above 1.800 f/sec will benetrate better on game than an identical bullet at an higher speed. More velocity will only provide better range.

It is for this reason that I use a 270 to shoot springboks at 300 yards and a 9.3 or a 458 for hunting in the bush.

quote:

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Originally posted by Andrea Sandri-Boriani:
I understand that the penetration of a bullet depends mostly on momentum (mass x velocity) and not on kinetic energy (mass x velocity x velocity).

On expanding bullets the higher is the velocity the faster the same bullet will expand, so losing velocity and consequently penetration.

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Thanks Andrea.....I think that's what Gerald is trying to say.

Every once in a while on the AR forums I get the feeling that someone asked "what time is it" and the replies are of "how to build a watch".

Gerard,
Thank goodness I do not have to realign my mind to any drastically new or adverse concept. The faster an FN solid goes, the deeper it penetrates, as long as it does not deform. And we all know that it takes something like a 55 gallon steel drum full of sand to begin to deform a GSC FN.

The idea of a bullet going to sleep within 4 to 7 calibers of the muzzle is news to me, but that is very good news.

I am going to see what happens when I try to order some more of your bullets.

Cheers!

quote:

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Originally posted by RIP:

I knew I shouldn't have believed 500groans on the yaw thing!

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Ron, I am sorry you misunderstood or do not recall (not suggesting dipsomania) my comments on yaw. So for clarification...

Garrett has stated that his FN bullets penetrate deeper than RN bullets because the FN bullets are shorter than RN bullets, and therefore do not have as much yaw, resulting in better penetration. I said that Garrett may be using heavy bullets, such as 540 grain lead in .458 cal., in barrels with a slow twist designed for light bullets (such as 300 to 400 grain 45-70 factory loads). If that is the case, then he may be experiencing excessive yaw with long bullets. If Garrett used a twist rate suitable for the slugs he is pushing, then yaw should not be an issue.

But I will say this: NOTHING beats a flat nosed solid for depth of penetration on body shots.

Let's simplify this. Bullets are like sex. The longer projectile will penetrate deeper if it does not bottom out first.

A little side note here folks.....and it is related!!!
When Weatherby first announced the .378 they took it on a cape buff hunt to prove its performance. On the hunt they shot (using solids) a big bull and the bullet exited and hit another buff behind it and again exited the second buff and killed a third one.....all with one shot.

At least this was their advertizing at that time and we all know that the manufacturer of a gun would not pull anyone's leg on stuff like this.

While I'm in tune with Will's statement that "there's no such thing as too much gun" I also believe there is such a thing as the WRONG bullet.

On expanding bullets, they will penetrate deeper with velocity to a point. However to much velocity will increase expansion which will decrease penetration Same happens on some cast bullets. Expansion or veering off course will limit penetration. With many cast bullets penetration decreases @ past 1950-2050 fps and above. This according to Garret and Corbon testing. Good luck.

500groans,
Thanks for the clarification.

I believe Gregor Woods explains and discusses penetration, shock, and killing power as well as anyone in"Rifles for Africa".He believes that too much velocity even in premium soft points can cause the bullet to expand too soon thereby limiting the penetration.He did extensive testing using boards stacked like slices of bread in a loaf. He reports that with soft points many loads penetrate less at higher velocities than at lower velocities. Another good read on ballistics,penetration, and killing power is "Ballistics in Perspective" by Mike Lagrange who was a cropping officer in Zim. He also discounts velocity as the paramount consideration in selecting a cartridge for stopping or killing power. These are not necessarily my views but both authors have shot a lot of dangerous game.

Of course. The only controversy is when one gets his tomato and apple confused, or even when he thinks that the banana will perform like an apple.

We musn't substitute an orange for an apple either.

quote:

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Originally posted by M16:
Let's simplify this. Bullets are like sex. The longer projectile will penetrate deeper if it does not bottom out first.

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Are you sure you're not from Arkansas?

To all: As mufasa mentions above, Ballistics in Perspective makes for interesting reading. Lots of issues discussed including penetration at different velocities, etc. The book is avaiable at Amazon.com The book is only 76 pages but it's packed with informtion.

-Bob F.

Ballistics in Perspective
by Mike Lagrange

About the Author:
Mike LaGrange, born in Southern Rhodesia, spent many years as a warden in Problem Animal Control for the Zimbabwe National Parks. Mike has shot over 6000 elephants and knows which calibers work.

Product Description:
Originally written in 1983 in response to a need to provide guidelines for prospective hunters under the 1975 amended Parks and Wild Life Act and provide for learner professional hunters embarking on a new career. The book was primarily directed at Zimbabwean hunters and sponsored for 1000 copies. It is essentially practical, dealing with the commercial weapons that were available at the time of writing in Zimbabwe.

# Paperback: 76 pages
# Publisher: Professional Hunter Supplies; 2nd edition (February 1, 1990)
# ISBN: 096248072X

With the greatest of respect to the work done by Mike LaGrange and Gregor Woods, their published works are of historical interest. Neither include the developments in bullet technology of the last 10 or 15 years. No fault of Mike LaGrange, the book was published before these developments came about. I would much rather heed the advice of Ray Atkinson, Johan Calitz and others who have experimented with the modern bullets in soft and solid and speak from a position of been there done that.

Gerard

You know that I've been using your bullets for years and I like them, still the most of the hunting, particularly of non dangerous game it is still done with conventional spitzer or round nose conventional bullets, that are definitively better performers at lower volocity.

I've personally witnessed a good friend of mine being charged by an impala ram after it was shot on the shoulder at less than 30 yards with a factory loaded 300 Weatherby Magnum.

The bullet completely disintegrated on impact and failed to incapacitate the animal, that was subsequently killed by a neck shot at about ten paces distance.

If my friend had used the same bullet at 308 velocity the first shot was going to be the only one needed.

I still have an unresolved feeding problem with your FN solids in my 458 Lott that is preventing their practical use. The biggest problem by far in my area is not penetration or trajectory but bullet deflection by the foliage and you know that the faster bullets are the more affected, particularly when spitzer.

For game of the size of a kudu I'm now looking for flat nose lead jacketed bullets at about 2.000 f/sec in 9.3 and 458 caliber, keeping solids as back up.

Hi Andrea,
Disintegration at high impact speed with jacketed lead bullets is a fact of life. Going back to the beginning of the 90s, the solution to this came with monometallic bullets. That brought another problem that is still with us today. Most of the monometal (expanding) bullets are too tough to expand reliably at slower speeds. So where the jackted bullets have a window of application that is at the lower end of the speed scale, standard monometal bullets should be applied higher up on the scale. You are using our HP range of expanding bullets, hence the problem.

With the HV bullets, we have developed a range that overcomes this problem completely and can be applied from 1900 fps impact speeds to way beyond 4000fps. HVs offer you the widest window of application there is. You should try the 230gr HV in your 9.3. See the performance here.

I would love to get my hands on that Lott. I have been smithing since '79 and fixing it for you would not be a problem. If it hassles with feeding an FN, it is probably marginally reliable with RN solids and will cause trouble sooner or later.

Hi Gerard,

If you can fix the occasional feeding problem I will use only your FN on the 458.

With the 9.3 I never had to shoot over 200 yards and I know how to compensate automatically the bullet drop at that distance.

The only bad shots I had during the last few years have been mostly depending on grass/foliage deflection and my priority is now to mantain the balistic of a 270 grains at 1.950 f/sec with a bullet shape that will act more as a punch and less as a wedge.

Shooting trough grass I verified that the wad cutter shape far more accurate than a spitzer shape and I'm now looking for a bullet cheap enough to be used for practice and good enough to be used on wildebeest and kudu (but mostly on impala and warthog).

In my opinion for practice and biltong hunting in my area FN copper bullets are not really required, as a certain amount of expansion is desirable, and the HV will not solve the deflection problem.

Obviously if I will have to take the 9.3 in a more open terrain I will certainly consider the 230 grains HV you suggested.

When are you coming to Phalaborwa? I have a few buffalo available at a reasonable price and maybe we can do some testing together.

Andrea,

Here are the reuslts of a study I made several years ago of penetration of FMJ and solids at different rotational velocities.

I have no idea if this correlates to elephant heads, body shots, or craters on the moon, but treated all bullets equally and probably is a meaningful representation of relative energy over unit of frontal area (penetration).

Andy

PENETRATION OF FMJ RN BULLETS IN 375, 416, AND 458 CALIBER RIFLES AT STANDARD AND ENHANCED VELOCITY AND ROTATIONAL VELOCITY.

C 2001 Andy Tillman

Boards Caliber Bullet Velocity Twist Shots/Comment

458 x 404 (Similar to 460 GA).

71 1/2 458 x 404 500 FMJ 2,367 fps 1-10 One to two more boards than 1-14 twist which had slightly higher velocity.

71 1/2 458 x 404 500 FMJ 2,367 fps 1-10

48 458 x 404 450 GSFN 2,450 fps? 1-12 Perfectly straight bullet path.

46 458 x 404 500 FMJ 2,334 1-10 Hit left edge. Exited side of stop-box. Tipped at 40 boards (13 more than 1-14 twist). Penetrated 10 boards more than 1-14 twist. Threw wood 30 feet!

28 458 x 404 500 Barnes X 2,334 1-10 Unstable. Expanded and turned 180 degrees. Fully sideways at 23 boards, traveled base forward until 28 th. Climbing (upward) wound profile like 5.45 x 39mm.

450 Ackley

70 1/2 450 Ackley 500 FMJ 2,400 1-14 1-2 boards less penetration than 1-10 twist.

69 1/2 450 Ackley 500 FMJ 2,400 1-14

36 450 Ackley 500 FMJ 2,400 1-14 Exited side of stop-box. Tipped at 27th, fully sideways @ 31 boards. Ten boards less penetration than 1-10 twist.

458 Winchester (BRNO 602 with 25 inch barrel).

62 Simulated 458 Winchester 2,030 1-10 (Down-loaded 458 x 404). Penetrated 3-4 more boards than standard twist.

59 458 Winchester 500 FMJ 2,021 1-14 Circa 1980 Remington/FMJ

58 458 Winchester 500 FMJ 2,105 1-14 Federal Premium/FMJ

39 ½ 458 Winchester 450 GSFN 2,050 1-12 Simulated 458

23 458 Winchester 510 RNSP 2,105 1-14 Expanded. Federal Premium.

21 458 Winchester 510 RNSP 2,021 1-14 Expanded. Circa 1980 Remington.

416 x 375 Improved (Similar to 416 Remington or Hoffman but with 1-10 twist).

71 416 X 375 Imp 410 Kynoch FMJ 2,400 1-12 Three shots. Very consistent performer. Kynoch is copper clad steel jacket like Hornady.

375 Improved (Similar to 375 Weatherby or 375 JRS), 22 ½ inch barrel.

71 375 IMP 300 FMJ 2,791 1-8

70 375 IMP 300 FMJ 2,791 1-8

50 375 Improved 300 FMJ 2,791 1-8 Exited side of stop-box. 13 more boards than standard twist that exited.

375 H & H (22 inch barrel)

65 375 H & H 300 FMJ 2,570 1-8 Penetrated 4 more boards than standard twist.

61 375 H & H 300 FMJ 2,570 1-12 Twice

37 375 H & H 300 FMJ 2,570 1-12 Exited side of stop-box.

NOTES:

Stop-box made from 12 x 12 inch square sheets of ¾ inch thick pine spaced ¾ inch apart.

Range, 25 yards

All FMJ bullets were copper clad steel jacketed Hornady unless noted otherwise. The Kynoch had a slightly more rounded meplat than the Hornady.

QUICK ANALYSIS:

A faster than normal rate of twist in both 375 and 458 caliber rifles at both standard and “improved†velocity levels resulted in 3-4 more pine planks being penetrated than at standard 1-14 or 1-12 rates of twist.

Rotational velocity was not as important as increased velocity. The 458 wildcats (2,400 fps) penetrated 10-12 more boards than the standard 458 Winchester. The 375 improved (2,800 fps) penetrated 6 more boards than the 375 H & H.

A very high rate of twist (1-8) resulted in a penetration gain of 4 more boards over a standard 1-12 twist in the standard velocity 375 H & H.

Rotational velocity of greater than 1-10 twist may be beneficial when using monometal bullets of high SD. These very long (1.6 inch) bullets may also benefit from careful design, keeping the center of gravity exactly the same as its center of form.

There does not appear to be such a thing as a “magic†velocity threshold of 2,400 fps as some observers have suggested. The 375 improved at 2,800 fps penetrated 9-10 more boards than at 2,570 fps.

No increase in penetration was noted using contemporary versus vintage 458 Winchester ammo. When loaded with the same 500 gr Hornady FMJ bullets, circa 1980 Remington 458 Winchester ammo actually penetrated one more board than higher velocity Federal premium ammo loaded in 2001.

Most bullets could be de-stabilized by an edge hit on the 12 x 12 inch boards, or an overlapping hit on previous shots.

The quicker twist bullets were somewhat more consistent than slower twist but not enough shots were made to verify this with absolute certainty.

When FMJ bullets did exit the side of the stop box, the quicker twist did so 10-13 boards later than the standard twist.

A 458 Winchester could have the same rotational velocity as a 450 Ackley just by using a 1-12 twist.

ROTATIONAL VELOCITIES TESTED:

1-14 @ 2,021 fps = 1,717 revolutions per second (rps).
1-14 @ 2,105 fps = 1,789 rps.
1-14 @ 2,400 fps = 2,040 rps
1-12 @ 2,050 fps = 2,050 rps
1-12 @ 2,400 fps = 2,400 rps.
1-12 @ 2,450 fps = 2450 rps
1-12 @ 2,570 fps = 2,570 rps.
1-8 @ 2,570 fps = 3,855 rps.
1-8 @ 2,800 fps = 4,200 rps.

In this thread many things are mixed up and apples are compared with oranges.
What came out as true:

Penetration depends on bullet construction and deforming bullets (soft nose) sometimes show less penetration at higher velocity because they give more resistance to the medium due to altering their shape.
But nondeforming bullets (solids) never can exhibit lower penetration when travelling with higher velocity, all other parameters being equal.

But there are still some mysteries about less penetration at higher velocities around, together with arguments presenting erroneous physical statements.

First, a simple logic: When the higher velocity bullet decelerates to normal velocity, it further should now penetrate normal. In summa: more penetration for the high velocity bullet.

Some basics:
The force, which is needed to penetrate, is F=d(m*v)/dt.
That means, the force equals the change in momentum with time. And is higher with higher velocity.
Stagnation pressure, besides the explanation given above, is basically a different term for the total pressure a moving object experiences. It is the pressure you can measure at the forward stagnation point of a body, it can calculated using Bernoulli´s equation. It is used to measure the velocity of an aircraft with the Pitot-tube, a very simple device. This pressure is produced by the moving body as the reactio according to Newton´s law.
It is increasing with velocity, but not stopping the object more than the normal deceleration by decreasing the energy capacity of the bullet.
It has nothing to do with lesser penetration at higher speeds.
Hands slapping water is a misleading example, not applicable here.

Precession by the bullet leaving the muzzle can result in angles of yaw up to several degrees and influence penetration at short distances. That a faster twist helps is confirmed by many authors. An extreme example was the bullet of the military G11, it was going to sleep at 80 yards!

Sectional density has to do a lot with penetration. Multiplying with velocity it gives a figure of momentum density, the basic number for all penetration research.
To overcome the drawback of the greater length of pure copper bullets, manufacturers recommend the use of lighter bullets, the greater muzzle velocity would compensate for the lower mass. This can accepted for normal hunting conditions, but applied to non-deforming bullets (solids) for dangerous game hunting it can become a desaster. The lower sectional density results in less penetration (see Penetration Index), because less weight normally can not compensated by more muzzle velocity in safe pressure limits.

There is another, very important reason to use bullets with a SD greater than 0.3: We don´t know exactly the drag function in animals and it must be very complicated. But one fact is for sure: The heavier bullets are less decelerated than the lighter ones. Heavier bullets loose less velocity during their travel through the target. That means: heavier bullets keep their momentum, lighter bullets loose more momentum on their travel through the body. And keeping momentum results in deeper penetration.

BTW off topic: Why do the military try to enhance velocity for maximum penetration? Reportedly speed up to 3000 m/s may go through an Abram M1 like butter.

Norbert.

No matter how many times you (or I) tell them, it just doesn't matter. They don't or won't believe it.

There is this constant reformulation of mumbo jumbo based upon irrelevant parameters, the latest being stagnation pressure!!

Apparently part of this is to sell bullets.

quote:

Originally posted by allen day:
It all depends upon who's leading the discussion, and whose pet theories are on the line.

If you'd compare someone's pet .45-70 with special hard-cast bullets to the .458 Win. Mag., then the answer is, "slower penetrates better."

If you'd compare that same obsolete .458 Win. Mag. to another guy's .450 Dakota, then the answer is, "faster penetrates better".

AD

WELL SAID, ALLEN!

Will,
If the technical stuff bores you or you do not understand it, you could do us the courtesy of refraining from snide remarks. Had you been paying attention, you would have seen this a bit higher up as it was my reply to the first time you asked what stagnation pressure has to do with penetration.

"When stagnation pressure is higher than the tensile strength of the bullet, it breaks and penetration is adversely affected."

You would have noticed that I said that this is in the context of expanding bullets and excludes monometallic solids.

Stagnation pressure is the reason why a bullet deforms on impact. Those of us who design and build bullets would be stupid if we did not take it into account. If you ask a question and I answer in good faith and you differ from me, bring on the reasons, not the smart alec remarks.

Norbert,

Designing and building solids is easy. Let us see you do some expanding bullets and then tell me again that stagnation pressure has nothing to do with penetration.

Your statement "Sectional density has to do a lot with penetration. Multiplying with velocity it gives a figure of momentum density, the basic number for all penetration research." is interesting.

It is of course true that two bullets with exactly the same momentum density number will penetrate equally. This means that a 300gr .375 bullet at 2500fps will penetrate exactly to the same depth as a 270gr .375 bullet at 2780fps if niether deform. Of course the Sd of the 300gr bullet is .305 and the 270gr bullet is .274 but we see here that Sd is no longer relevant.

Norbert, you must also be careful about giving out technical information about your experience and the bullets you have designed and sell. Will does not like it and believes it is a ploy of yours to sell more bullets.