This is in reference to solids only and mostly to meplate shape. Which shape would cause the largest wound channel considering the information Norbert has posted in the past about his Super Penetrators. His reference to the cup at the nose of the bullet forming a gas bubble that encapsulates the bullet and increases the penetration and straight line travel in an aqueous material such as Buffalo internals. Would a .475 bullet with a flat nose of .410 and tapering to caliber cause more damage than a .510 bullet with a flat nose of .375 tapering to caliber. What do you think?
Take care,
Dave

Good question, but one difficult to answer. Apparently, from reported results, flat nose bullets tend to deflect less which in theory would give better penetration.

The idea behind the German torpedo (Norbert's flat protruding disk) is to create a low presssure region behind the disk which causes the liquid to vaporize, hence decreasing friction drag. I have my doubts as how much effect this could have in the relatively short travel (penetration) in an animal. But it might be true.

The flat disk may also tend to reduce deflection and then give greater penetration, having a geater effect than the bubble formation.

I have used "relatively" flat nose solids such as the TB and Speer AGS. From what I have seen, the PI correlates better with penetration than any effect of the flat nose.

And flat nose bullets that are really squared off flat, or nearly so, give me the creeps when worrying about potential feeding problems, especially in the heat of the moment.

Also, IMO, it is always a trade-off between penetration and energy, which are probably both more important than bullet shape (within reason).

For really big stuff, the penetration of the 416's make up, to an extent, for their lack of horsepower. The Lott is a step up but one has to suffer the greater recoil, which is my limit for range practice.

If you can stand it, the 505 Gibbs and 500 Jeffery are much better, but they are killers recoil wise (in a rifle light enough to carry).

The ideal would be a 500 gr. bullet with a PI of the 416's, but ouch, so much recoil!

[ 10-11-2003, 11:14: Message edited by: Will ]

Get a copy of Veral Smith's book about shooting lead bullets out of rifles. He is the owner of LBT(Lead Bullet Technologies). He has done extensive testing on meplat design for penetration and wound channels with his bullet designs.

Do I understand these effects correctly. I have done some research on this, but I am not formally schooled so please bare with my terminology. Here goes.

The flat point generates a low pressure bubble in front of the bullet, which shifts the center of pressure forward of were it would otherwise exist. This shifting of the center of pressure forward, increases the moment arm that exists between the center of pressure and the center of mass. This latter effect, the increased length of the moment arm between centers of pressure and mass, then reduces the bullet's yaw tendency resulting in a reduced shank drag and therefore greater penetration.

The other effect of the flat point is to increase the drag at the nose of the bullet, which is the result of the creation of the low pressure bubble. This effect slows the bullet faster, which adversely effect penetration. This is hte case since ulitmately, the penetration is a function of the shear force generated by the bullet. Shear force is by determined by the velocity rate change versus time, as well as, the bullet's mass. So bullet deceleration and mass retention become very important as well with regard to penetration.

So the bullet must be designed to achieve a balance between the increased yaw stability of effect one and the increased braking of effect two. With the goal to achieve an optimum reduction in total drag. I do not pretend to know the answer to the original question, and apologize if it seems I hijacked the thread. It just seemed to me that the right people were here to ask my questions too.

Is that close to reality? If so, great, can someone please explain in simpler terms that I may really understand? Thanks.

[ 10-11-2003, 17:40: Message edited by: Judy ]

Good replies. I'm thinking of .510 bullets of either the 505 Gibbs weight of of 525 grains or the Jeffery bullet weight of 535 grains at velocities of 2300 or 2400 fps. The .475 bullet would be the Bridger 540 grain at 2400 fps so that things are comparable weight wise and velocity wise although the .475 would have a much higher sectional density. Judy makes a good point of the balance between the flat nose shape and the effect of better penetration due to the the shape itself. Personally I think that any of the bullets mentioned at the velocities given would have enough penertration. Ray was mentioning that the Buffalo that he shot with the flat nosed Bridger solids showed the same tissue damage as a soft point bullets used before. I was curious if the larger flat surface area would cause more damage internally than a larger caliber bullet with a smaller flat surface area.
Norbert nice to hear from you and thanks for the reply. I think you answered what I was asking about.
Take good care,
Dave

Pls visit my website.
Penetration length of solids is limited by the bullets flight becoming unstable in the tissue. This is caused by a breakdown of the water vapour bubble generated at its front and which covers the whole bullet. Then the bullet turns, tumbles, veers and leaves the straight path, in some cases having still ample energy for further sideways penetration. In really wet packs (80 % water) a conventional bullet leaves the setup after about 30", a SuperPenetrator is still going straight after 100". With body shots on elephant, you observe no exit, the bullet may be stick anywhere in the body, but on smaller animals the bullet mostly exits. The SuperPenetrator maintains the gyroscopic stabilisation in the tissue. Flat nose bullets may also show this effect, but not as efficient and stable as the SP.
The point of pressure is at the front of the disk, but there is no gas bubble in front of it.
Shank drag is marginal, no contact to the tissue itself.
The balance between drag and wounding depending on the disk or nose shape and the stabilisation effect was the question Dave introduced.
The Penetratin Index PI (Alphin) reflects the acting forces on bullets of similar shape and can also used for SuperPentrator bullets. The PI of conventional bullets and SP bullets cannot be compared.

I have been using the flat nose solids for years, early on I filed them flat and used them up front with RN in the magazine because they wouldn't feed..

Then GS Customs shows up and I ordered a truck load of them in 416, 404 and .375 and they had what I had been advocating, a cutting shoulder. I was told by some internet expert, who I have not heard from in awhile, that the cutting shoulder made no difference and they could prove it on paper, but I disagreed as I had seen the results of the Keith simi wadcutter in pistols and was impressed and wanted to apply that to rifles...Just made since. I tried to get all the US makers interrested but they smirked and said no way...

The GS Customs killed like the hammer of Thor, they penitrated stright as an arrow and cut a neat cookie cutter entrance hole and a even larger exit hole than any solid I had previously used...Johan calitz had used them for years and would use nothing else...internal damage was between that of a SPRN Woodleigh and a regular solid...I used these for several years with satisfaction, but alas circumstances prevent me from further use of that bullet..They also worked very well on plainsgame in my big bores and left some near 1" exit holes on Zebra, Kongoni and eland.

This year I used the Bridger bullet, a clone of the GS Custom but with a much more apparant cutting shoulder and here is what I observed on 7 buffalo kills...the cutting shoulder apparantly pushes the skin into the body cavity about 1/8 of an inch and shaves the hair around the bullet hole, and at the same time it cuts a perfect wadcutter type hole in the skin that lets out a ton of blood, the exit hole is also a clean cut caliber size hole and allows a rush of air inside the body cavity that I believe forces the blood out both sides up to 5 feet on one ocassion..It killed them quick and they mostly didn't make a lot of tracks..I have some interresting photos of these entrance wounds...On Coup de grace shots a stream of blood about 10 to 12 inches was the norm...

Saeed also had some great results with his Walter hog bullets on Buffalo and penitration in one case was in the ham and OUT the neck almost behind the ear in striaght penitration with a small amount of actual expansion and a flatened point to about 40 caliber from his .375/404....very impressive..

Penitration in all cases with these FN solids has been more than enough and better than any RN, stright and true has been my experience. Johan shot an elephant in the hip and recovered a GS bullet from behind the ear, thats impressive....

As to feeding, the GS fed in most of my guns with a couple of exceptions but the Bridgers feed as slick as snot in all my guns so the winner goes to the Bridger bullet in that very important catagory..

I understand and am hoping Woodleigh gets on the band wagon with a FN solid that will work in double rifles and Bridger obtained some material simular to GS and with its low pressure, pressure rings they will also do well in the older double guns with less pressure than any other bullet...

Ray,
What caliber rifle did you shoot on the trip and what was the diameter of the flat nose on the Bridger bullets as well as the bullet weight? I've found that both the GS and the Bridger feed flawlessly in my 470's. I think the 540 at 2400 fps with a flat nose of .410 should be devestating.
Take care,
Dave

I suggest you give my gunsmith a call.

http://jackhunt.hypermart.net/

Jack is an expert hunter, gun and cartridge designer, and, knows more about large, read 500 caliber cartridge designs, then most will ever know.

Unlike myself, he field tests his 500 conversions, and, I've handled both his 500 JRH, and a beautiful ruger one, in 510 wells. I'm
going to have him build me one, on a 550 CZ 416, after I get my first couple FA's from him, first a 510 JRH, and second, a 22 lr FA 83(another expert said the 22 lr FA83 was simply the most accurate Pistol he EVER fired.).

" I got to get me one of those!!!!!!"

gs

[ 10-12-2003, 09:35: Message edited by: Socrates ]

As Gerard S. confirmed earlier, his FN solids from relative soft copper deforms a little on impact, resulting in a protruding shape of the nose, very similar to the SuperPenetrator.
So both, the GS FN and the SP show very similar effect on game, based on the same physical effects. But what the FN should do, is an inherent construction detail of the SP and not dependend on chance.
Another appraoch to the stabilized Supercavitation effect is the Northfolk design. I don�t know how the Bridger is doing.

Hi Norbert,
When I get back home I'll take a picture of the 540 grain /bridger and post it up so you can have a look at it. It is very similar to the GS Custom but the edge of the bullet is a lot sharper from the flat section than the GS custom which is rounded somewhat.
Take care,
Dave

.

Alf,

A blunt nose projectile is going to create a bigger cavitation volume than a pointed bullet, all things being equal.

How much effect this is going to have on pressure waves, penetration, or straight-line penetration is subject to interpretation, IMO. What effect from contact with bone this has on penetration is also an interesting quesstion, considering all the millions of variables in shooting game.

If they work as proported, I think it's great.

[ 10-13-2003, 11:16: Message edited by: Will ]

470Mbogo - Excellent Topic.

Norbert - Don't be such a stranger around these parts. Bring us up to date, as to your ele hunting. Still staying with the Lott?

[ 10-13-2003, 17:08: Message edited by: Nickudu ]

Nick,

Sorry, but my english is not sufficient to understand what you are saying. Why a stranger? My comments for sure are sometimes clumsy, therefore I have to repeat some statements often.
What do you think should be updated?
Re elephant hunting: this topic is on terminal ballistics. But BTW,
the SuperPenetrator seems to develop into magic bullets. Last trip for testing I shot 7 cows in 9 days, other parties in the same area shot nil in 10 days.
And always with .458 Lott. Best DGR cartridge for me.

Norbert
SuperPenetrator

I just got back this week and have not completely read the entire thread so forgive me if I repeat some things.

The flat nose bullet profile is nothing new. Pistol shooters have had success with it for years. It is only recently that it is being used by a substantial number of rifle shooters on DG.

Norbert's description of what happens is 100% accurate. The flat nose or disc (as on his bullets) creates an air "bubble" around it as is passes through liquid material. This bubble is the reason they function so well. They penetrate true to course and do a lot of tissue damage. The bubble can have substantial diameter, up to and over 3", this is what does the soft tissue damage similar to a soft. You don�t get the fragmentation and momentum loss like a soft but it does do a heck of a lot of tissue disruption. Ray's comments that the Bridger solid gave similar results to the surrounding tissue bear this out.

Norbert's disc size can be controlled and this in turn will effect penetration. What we've done is settled on one formula for all of the bullet sizes. We are going for a "bubble" of 6-8 times the bullet diameter. For the larger calibers .375 and up one formula works well but we tweak that formula a bit from .338 to .358 to achieve the same results in those calibers.

We were also concerned with feeding and had to take that into consideration. As of yet there has only been two occasions where he had any kind of feeding issues in hundreds of rifles we have tested. As it turned out the rails needed some work. They were both as new factory rifles and were rough as hell. We tried some spitzer type bullets and while they functioned it was not that smooth and I would never consider taking such a rough feeding rifle after DG.

For close in DG hunting the FN is absolutely the way to go. IMHO

For those interested my 2 FFLs came in Saturday�s mail. I will have the website up by weeks end. We are turning as I type.

John
Bridger Bullets Inc.

I forgot to add a couple of pictures of 470Mbogo's bullets.



The first two are 470Mbogo's .474 - 540 gr with a .410 meplat.
then a .510 bore rider and a .700- 1200 gr on the far left you can see the start of a 50 BMG.
John

470 Mbogo

I was using the the 416 with Bridger solids and also took some 375 for my PH....the 416 flat measures about .300 and the 375 goes .285, the cutting should is very pronounced and hard and sharp and it mikes at 416 and 375...

Interresting to you and Alf I suspect is the fact that the cutting shoulder obviously shaved the hair for a 1/4 inch (rough guess) around a perfectly round and open entrance hole, the entrance hole itself was about caliber size and did not close up giving me the cookie cutter impression and it let out a lot of blood and did a awsome amount of internal damage very close to the internal damage of a 450 gr. Woodleigh SP but not quite..

I got the impression that the bullet pushes the skin in for some ways, thus the shaving the hair then cuts a caliber size wad of skin out and when the skin springs back to normal it is shaved around the entrance hole. Thats all I can figure...

But I guarentee you that it kills tons better and leaves considerably more blood on the ground than any RN solid...

Pierre Van Tonder will be using the Bridger FN solids in his 500 Jefferys exclusively...He was impressed with the results of the 416 and 375..I shot some plainsgame with his .375 and the Bridger solids for our game scout headquarters. They worked like a charm with shoulder shots and no waste....

Norbert, When we say, "don't be such a stranger", it is to say that we wish to hear from them, more often. A compliment. A note of encouragement.

BTW, I already knew how many ele you shot, last trip. I thought others here might like to hear about it.

John/Bridger Bullets,

How do you know that the "bubble" is 6-8 times the bullet diameter? Was this determined in water using high speed photography?

Where is this 6-8 diameters measured? Since there is no bubble at the leading edge of the bullet, it seems impossible that this bubble diameter could be anywhere near the bullet. Maybe downstream?

Admittedly, separation of the flow and cavitation can occur due to the blunt leading surface, but this seems to be getting exaggerated somewhat.

[ 10-14-2003, 02:41: Message edited by: Will ]

Will,
We used a few different methods to determine tissue upset. We used high-speed photography, wet newspaper, gelatin, layered colored sand and a couple of others. The bubble is in fact in front of the FN. The 6-8 times caliber is an average of what we found with the current nose profile.

You can liken it to a large truck on the highway that is passing you. You can feel the wind displacement before the leading edge of the rig gets to your rear bumper. This wind gets more pronounced as the truck goes by but it does hit you before the truck.

John

fritz454 - I have a few questions. At what bullet velocity is the bubble diameter equal to 6 to 8 bullet diameters? Is this effect even velocity dependant? What happens when one of these flat pointed bullets hits a bone nonuniformily? You know, like a glancing blow, does the bullet tumble or stay true to it's original path?

[ 10-14-2003, 03:49: Message edited by: Judy ]

Judy,

Within normal hunting velocities 2000-2600 fps, velocity has only a small impact on the bubble. Lower velocities have a slightly smaller cavity while driving them faster has a slightly larger bubble. If you drop the velocity below a certain point the bubble never establishes itself. That exact velocity is dependent on too many things to give you an exact number but suffice it to say it is well below any acceptable hunting impact velocity.

This is not an exact science since the exact conditions at impact can never be 100% duplicated and you can find exceptions to the above statement.

The size of the bubble is related to the shape of the nose but mostly the size of the meplat. The larger the meplate the larger the bubble but the less penetration and vice versa.

If the bullet passes through a bone the bubble is wiped off and then reestablishes itself once through. If it is a glancing contact that section of the bubble is wiped off and again reemerges after a short time. Since a FN is not as susceptible to tumble as a RN penetration in all of the above cases is straight with the FN.

It has been my experience that regardless of the type of hit on bone, edge on, through or glancing, the bullet path remains straight. I have shot thousands of these bullets and have never had one alter its course to any appreciable amount. I would of course be lire if I were to say that it would never happen. It very well may but I've seen no indications that deflection or tumbling is a problem and I've tried to induce those exact problems.

Norbert's work on this is exceptional and I would advise you to look at his web page. He has photos and detailed explanations on the effect.

Although, I guess, we are in competition with each other I have a lot of respect for his work and my own work has only supported his and his conclusions.

John

John/Bridger Bullets.

The pressure wave will exist ahead of the bullet up to the point of the speed of sound in water/flesh, whatever that is (5,000 ft/s in water, anyway), but not a vapor bubble.

Once the bullet reaches and surpasses the speed of sound there is no pressure wave ahead of the bullet (probably even greater than 5,000 ft/s in flesh).

The pressure wave may be more pronounced (larger in comparison to diameter) with a FN bullet than a pointed bullet but there is still no bubble ahead of the front of the bullet. The only reason there could be a bubble is from the separation of flow due to a velocity increase and associated pressure decrease and hence possible vaporization of the liquid (water), which is only downstream of the bullet's leading edge.

Hi John,
Thanks for posting the photos of your bullets. They feed perfectly in both my 470's. Glad your getting into production and have all the t's crossed and I's dotted with big boys.
Ray,
Thanks for the details on the calibers and bullets used. From the description and measurements given it sounds like the .410 flat nose should be devestating. I think your idea of the hide pushing in and the cutting shoulder cleaning the hair off around the entrance hole is smack on. I'm sure looking forward to a getting a chance to try them out on some Buffalo.
Norbert,
Like Nick said it's good to hear from you and have your input on subjects posted. Your like the Guru of external ballistics.
Take good care,
Dave

Norbert:

Just curious how deep in water could be your bullets (for example .416 at 2400fps) dangerous ? Could you design bullet for maximum "penetration" in water (for antishark weapons etc.) ?

Jiri

/

John:
>>The flat nose bullet profile is nothing new. Pistol shooters have had success with it for years. It is only recently that it is being used by a substantial number of rifle shooters on DG.
--right, but nobody gave a well-founded physical theory and now we can optimize the underlying effects.

>>It has been my experience that regardless of the type of hit on bone, edge on, through or glancing, the bullet path remains straight. I have shot thousands of these bullets and have never had one alter its course to any appreciable amount. I would of course be lire if I were to say that it would never happen. It very well may but I've seen no indications that deflection or tumbling is a problem and I've tried to induce those exact problems.
--That is what I repeatedly mention and it is an argument against another theory of stabilization, the shoulderstabilization, propagated by european scientists.

>>Although, I guess, we are in competition with each other I have a lot of respect for his work and my own work has only supported his and his conclusions.
--There is no commercial competition, my work is dedicated to the fraternity of DG hunters and not closed in any way.

>>The bubble is in fact in front of the FN.
--No, that is physical impossible. We should not mix up signs of differences in the refractive index on photos or gelatine or the like. Here Will is right:
>>The pressure wave may be more pronounced (larger in comparison to diameter) with a FN bullet than a pointed bullet but there is still no bubble ahead of the front of the bullet. The only reason there could be a bubble is from the separation of flow due to a velocity increase and associated pressure decrease and hence possible vaporization of the liquid (water), which is only downstream of the bullet's leading edge.

Jiri:

>>Just curious how deep in water could be your bullets (for example .416 at 2400fps) dangerous ? Could you design bullet for maximum "penetration" in water (for antishark weapons etc.) ?
-- My experimental setup was not sufficient (only 100") to measure the maximum penetration. A special design is possible.

Alf:

>>It is claimed by some here that the stripping, cutting of hair and hide upon entry is a "good thing".
--For sure. A european hunter (and the cutting shoulder is developed in Germany 80 years ago) looks not at the hide, but he investigates the hairs laying on the ground where he shot the animal, which normally has disappeared into the bush. He than can estimate the spot where he hits the animal, as he will do with the blood trace from the exit.

>>As it is determined by the amount of water in tissue the size of cavity will differ as it passes through different tissues of varying type
(water content) thus subsequent stability should be negated if non water containing tissue is encountered ?
Lets say our shot path takes us through skin,
1 inch thick as it is on the brisket of a buffalo, then hits bone followed by lung (low water lots of air, then liver (Lots of water)and then entry into the abdominal cavity where it encounters the contents of the rumen (compacted grass etc), where is our cavitation theory now?
--always working. See posts above from John and me. If the water content is too low, another mechanism of stabilisation is observerd, also preventing tumbling. If water content again is sufficient, the bubble will reestablished.

>>Up to this point barring the liver supercavitation is a theory only as my conventional pointed or round solids are still on course to where is stops just under the skin in a direct line from front to back in more than one buffalo.
--from stern to stem in a buffalo? pointed solids: never stable. May by they turned 180� and than stayed on course by chance. RN on average are 30" on course.
>>the minute your wide meplat bullet hits bone the stability should be the same as a pointed bullet as the supercavitation bubble is not present?
--even in solid targets the pointed bullet is far more sensitive for tumbling then the RN or FN.
But the usual situation of a hunting bullets path is mainly water containing tissue.

You are right, wet newspaper is a poor medium for testing penetration as all other media, if the poor hunter doesn�t know what he is doing.
And for armour piercing bullets I have other proposals, not the SP.

Norbert

Will
The largest cross section of the cavity usually occurs near the trailing edge of the bullet but this seems to change as the density of the media changes. Despite what you may believe there is, in water, a thin region in front of the nose where the cavity begins to form. It is very close to meplate diameter at this point and grows in size along the length of the bullet. Once past the base the cavity begins to shrink.

ALF

The striping of hair is indicative of the punch cutting going on. The cutting shoulder acts like a punch but since there is no die behind the skin there will be distortion of the hide until such time as the shoulder cuts the hide. I would agree that to a much lesser extent this is true of all bullets. The hide/skin is rubbery and will indent before being penetrated. The amount of indentation will be less as the nose of the bullet gets sharper but either way some roll over into the wound would be caused by friction between hide and bullet.

All tissues that I am aware of contain water. The concentration may change but all have water. You are correct that the cavity changes according to the density of the tissue but that does not negate the effect on those tissues. Just because it is not pertinent to passing through a bone or less of an issue in low water tissue compared to high water tissue doesn�t mean it is irreverent at bringing down an animal.

We've used several media tests because none are perfect. With all due respect to Mr. Hundt any consistent media is useful as a reference. None are perfect except the intended end target but one or two or ten or one hundred is not a sufficient sample size to draw up a conclusion since none of those shots will be exactly the same and some how strapping a high speed camera to a buffalo before the shot would be difficult.

Your description to what happens to bone is accurate and is the reason a FN tracks straight and penetrates so well. If its good enough to get through plating then what chance does a bone have.

I don't know your training but it sounds as if you are a forensic scientist. If so it is important to notice the variables from your field to the hunting field. The science of GSWs, I would speculate, usually involves expanding bullets, mostly pistol bullets although FMJs and wad cutters enter the picture the velocities are so low that a case can be made that it is apples to oranges. Also, the structure of the human body is extremely frail compared to DG not only in size but in toughness.

I am not trying to be confrontational but informative as to what I have seen and experienced.

John

John/Bridger Bullets,

I think the bottom line here for hunters is that if they work as advertised, it is just great.

To really evaluate such claims, hundreds of buffalo or whatever would have to be shot under nearly identical conditions. Otherwise we have to live with antecdotal testimony, which is okay.

I think there is a tendency, though, to make claims or state supposed facts that aren't true (bubble in front of the bullet), when such statements are not really necessary. Hell, if they work, so be it.

There are a lot of "discoveries" put into practice that are not really understood from a physical science basis. IMHO, I just would let it go and make bullets!! Testimonies sell.

In addition to being a fabulous hunting bullet design, the Bridger Bullets are astoundingly accurate. I have shot some of the best groups of my life with them.

Thanks Norbert. As always, your posts are educational and informative.