Reverse bullet legend

[TranterUK]

Thought this may interest some,

The reverse bullet legend comes from WW1. In short it went that the Germans, faced with the first Tanks, invented by the Brits discovered that their 7.92 rifle bullets bounced off the steel plate. But if they reversed the bullet in the case, so it flew backwards it would penetrate the steel. I knew of the story but few believed it, and certainly not me.

Well I recently saw this tried out on a documentary, and guess what? It worked! a hole in the steel plate was formed with fragmentation of the plate thrown out behind. The bullet disintegrated.

Strange, but as it turned out, true.

[45nut]

That is weird.

[Lotsdragon]

LOL well that is a horse of another color!

[olmossbak]

Originally Posted by TranterUK

Thought this may interest some,

The reverse bullet legend comes from WW1. In short it went that the Germans, faced with the first Tanks, invented by the Brits discovered that their 7.92 rifle bullets bounced off the steel plate. But if they reversed the bullet in the case, so it flew backwards it would penetrate the steel. I knew of the story but few believed it, and certainly not me.

Well I recently saw this tried out on a documentary, and guess what? It worked! a hole in the steel plate was formed with fragmentation of the plate thrown out behind. The bullet disintegrated.

Strange, but as it turned out, true.

What about the spent cobalt 7,62 bullets supplied to the Afgans to use against the Russians? Are you familiar with that story?

[TranterUK]

Originally Posted by olmossbak

What about the spent cobalt 7,62 bullets supplied to the Afgans to use against the Russians? Are you familiar with that story?

What do you know?

[Pistolenschutze]

Originally Posted by TranterUK

Well I recently saw this tried out on a documentary, and guess what? It worked! a hole in the steel plate was formed with fragmentation of the plate thrown out behind. The bullet disintegrated.

Strange, but as it turned out, true.

Interesting, Tranter. It surprises me that a bullet without an ogive could penetrate steel. On the other hand, shaped charges work somewhat on that principle, the idea being for the projectile to burn its way through the material it impacts creating spawl.

[Suwannee Tim]

That sounds like spalling where a chip files off the inside of the armor. HESH, high explosive squash head shells are designed to do this. Shaped charges are different, they melt a hole through the armor.

[308 at my gate]

I would have to see it to believe.

[olmossbak]

Originally Posted by TranterUK

What do you know?

I know nothing, just something I heard somewhere.

[olmossbak]

Originally Posted by Pistolenschutze

Interesting, Tranter. It surprises me that a bullet without an ogive could penetrate steel. On the other hand, shaped charges work somewhat on that principle, the idea being for the projectile to burn its way through the material it impacts creating spawl.

Shaped charges detonate, or rather burn, a set distance from the armor and the copper jet created burns through the armor. That is why stand-off armor works against the RPG7, etc. It is the grating you see on the Strikers, aka armored Renaults.

[TranterUK]

I can tell you what I saw. Much to the surprise of the Army guys running the test, who doubted it would work and said so, a large hole was made in the steel plate, with peppering from impact behind.

It occurs to me that like a small shaped charge the base of the bullet may have been concave, I dont know, but a large hole was made.

I for one found this fascinating. If you reverse a .30 bullet in its case and fire it at plate steel, it seems it will make a hole, where it would not when fired point first. An old story that seems to be factual.

[kutaho]

Originally Posted by TranterUK

I can tell you what I saw. Much to the surprise of the Army guys running the test, who doubted it would work and said so, a large hole was made in the steel plate, with peppering from impact behind.

It occurs to me that like a small shaped charge the base of the bullet may have been concave, I dont know, but a large hole was made.

I for one found this fascinating. If you reverse a .30 bullet in its case and fire it at plate steel, it seems it will make a hole, where it would not when fired point first. An old story that seems to be factual.

Good logic

[Pistolenschutze]

Originally Posted by TranterUK

I for one found this fascinating. If you reverse a .30 bullet in its case and fire it at plate steel, it seems it will make a hole, where it would not when fired point first. An old story that seems to be factual.

It does make sense if you think about it, Tranter. Perhaps you remember reading about the steel plates the Germans used in WWI to protect their snipers sent out into No Man's Land to shoot at British troops. For some time the British could do relatively little about them since the .303s they were using simply would not penetrate the steel. Someone got the bright idea to send out a call to the civilian population for some African caliber double rifles, calibers such as the .577 and .600 Nitro Express. It turned out that those heavy, blunt-nosed bullets made short work of the German steel! I've seen photos of the German steel protective plates with nice, neat half-inch or better holes drilled right through them, and doubtless the sniper behind the steel!

[TranterUK]

Originally Posted by Pistolenschutze

It does make sense if you think about it, Tranter.

Perhaps we should get mythbusters on it?

[Pistolenschutze]

Originally Posted by TranterUK

Perhaps we should get mythbusters on it?

I think they much prefer to just blow things up, Tranter, not make neat holes in it. Perhaps if we suggested they place about five lbs of C4 behind the steel plate it would interest them more.

[delta13soultaker]

Originally Posted by TranterUK

Thought this may interest some,

The reverse bullet legend comes from WW1. In short it went that the Germans, faced with the first Tanks, invented by the Brits discovered that their 7.92 rifle bullets bounced off the steel plate. But if they reversed the bullet in the case, so it flew backwards it would penetrate the steel. I knew of the story but few believed it, and certainly not me.

Well I recently saw this tried out on a documentary, and guess what? It worked! a hole in the steel plate was formed with fragmentation of the plate thrown out behind. The bullet disintegrated.

Strange, but as it turned out, true.

Tranter, from my understanding of the mechanics of metal/steel/alloy armor penetration.....

The explanation is simply that backwards, the bullet fails and flattens on the plate, transferring all its energy into one point and spalling the back.

That was actually a primitive method of AP ammunition production....they made bullets that were designed to flatten on the armor and spall the other side. A conventional bullet just bounces off.

*This is totally opposite of the heavy metal penetrator method; although both kinetic, different method, with a heavy metal penetrator being drastically more efficient and with more effect on what's behind the armor.

**This is absolutely nothing like how a shaped charge penetrates armor. A HEAT projectile uses chemical penetration as opposed to kinetic force. HEAT is less efficient than heavy metal penetrators, but in low velocity weapons it is the only realistic method.


So here is your answer though...the bullet flattens on the plate and the instant energy transfer spalls the back. (This is one of several principles you learn while learning to engineer, teach, and build improvised munitions.)

[nightfighter]

Originally Posted by olmossbak

What about the spent cobalt 7,62 bullets supplied to the Afgans to use against the Russians? Are you familiar with that story?

Spent cobalt???

[millwright]

Nice tale, Tranter !!

Re the "tests"; what was the "grazing angle" of bullets penetrating the "armour" ? (We'll leave out of discussion the type of steel used in the target FTTB.) On a near 90' angle the base-first bullet would have a lot more "bite" into the steel, consequently better energy transfer resulting in spalling or holing of the plate.

Nose first, a cupro-nickel jacketed bullet spinning at 100K rpm would likely fragment from to nose back due to the torsional stresses set up on impact. I recall the Germans settled for a monster 12mm Mauser-pattern bolt rifle as an anti-tank weapon. It wasn't popular with the troops assigned to tote it....

Many years' back we did an impromptu test at the farm. The target was a 5/8" MS steel plate at 150 yds. The cartridges were a 7mm Rem Mag at around 140 gr vs a .35 Rem with around 165 gr. "Corlokts" as I recall. The 7 mm had no problem penetrating mild steel. The .35 dimpled it. When we "examined the evidence", I noted star patterns of copper on the front side, which leads me to conclude the nose of the bullet "broke up" and only the base penetrated. The .35 produced a shiny copper-plated divot in the steel.

Trouble with any of these "comparisons" is establishing a base line. Early mass-produced steel was inconsistent in hardness and tensile strength. Witness later discoveries about the Titanic. >MW

[USMC-03]

Originally Posted by delta13soultaker

Tranter, from my understanding of the mechanics of metal/steel/alloy armor penetration.....

The explanation is simply that backwards, the bullet fails and flattens on the plate, transferring all its energy into one point and spalling the back.

That was actually a primitive method of AP ammunition production....they made bullets that were designed to flatten on the armor and spall the other side. A conventional bullet just bounces off.

*This is totally opposite of the heavy metal penetrator method; although both kinetic, different method, with a heavy metal penetrator being drastically more efficient and with more effect on what's behind the armor.

**This is absolutely nothing like how a shaped charge penetrates armor. A HEAT projectile uses chemical penetration as opposed to kinetic force. HEAT is less efficient than heavy metal penetrators, but in low velocity weapons it is the only realistic method.


So here is your answer though...the bullet flattens on the plate and the instant energy transfer spalls the back. (This is one of several principles you learn while learning to engineer, teach, and build improvised munitions.)

It seems to be much the same principle as used to make round holes in plate steel with a punch press. I would also make the assumption that in combination with this principle, the bullet would also have to strike the armor plate at an almost perfect perpendicular angle. Great practical science...

[delta13soultaker]

Originally Posted by USMC-03

It seems to be much the same principle as used to make round holes in plate steel with a punch press. I would also make the assumption that in combination with this principle, the bullet would also have to strike the armor plate at an almost perfect perpendicular angle. Great practical science...

Yup. It was primitive and obsolete fairly quick. Sloped armor wasn't yet very common, except by coincidence.

[RunningOnMT]

If you think about it, this makes sense. At first thought you would think that a pointed or more tapered projectile would penetrate more but actually this shape round would tend to collapse or mushroom more on impact thus dissipating much of it's energy. The larger, flat, and less tapered end of the bullet would "break" the metal much like using a heavy hammer.

[delta13soultaker]

Originally Posted by RunningOnMT

If you think about it, this makes sense. At first thought you would think that a pointed or more tapered projectile would penetrate more but actually this shape round would tend to collapse or mushroom more on impact thus dissipating much of it's energy. The larger, flat, and less tapered end of the bullet would "break" the metal much like using a heavy hammer.

Yeah the steel core bullets of post WW1 would usually shatter on armor plate.

The Polish answer was to make a long 7.9mm cartridge based on the Mauser, but fired at much higher velocity. The bullet, they designed to flatten on impact. It retained 100% of its mass. Inside 100m, it would spall a 1" armor plate; inside 300m it could still spall 1/2" armor plate. The bullet was effected not very much by the typical armor slope found in the beginning of WW2. (Slope back then was < 30 degrees, unlike today where 45+ degrees is common.) In the beginning of WW2, the Polish used the weapon a lot against light armored Nazi vehicles and could kill a Panzer in urban terrain at close distance. When the Nazis beat Poland, they actually captured enough of those weapons to use on the Eastern Front against the Soviets, then the Soviets were so impressed with the rifle design (not the bullet) that they adopted part of it for their own 14.5mm anti-armor rifle.

The proliferation of heavy metals harder than steel successfully used to make penetrators, and the success at portable weapons that fired HEAT rounds, eventually made the technique obsolete. It is still a cheap and viable principle of armor penetration today. With some ingenuity, you could refit a resistance with rifles capable of killing APC's in urban terrain and without addition resources than what they already have.

[Teejay9]

Tranter, would this be comparable to a "dum dum" bullet? I believe they were outlawed in WWI. Wouldn't that work just as well, if they flattened the front end? TJ

[Suwannee Tim]

Originally Posted by 308 at my gate

I would have to see it to believe.

Alright, I will give you an example you can see. Find a pane of glass that has been shot by a BB gun. The part that is knocked out, a cone shaped fragment on the far side of the pane is the result of spalling. It is a well known phenomenon induced when a high velocity projectile hits a brittle material resulting in a relatively inelastic collision and high and sudden transfer of momentum. The angle of incidence has to be nearly normal, i.e. 90 degrees. The armor has to be relatively brittle, it will not work on ductile materials. The analogy to the punch press is correct. This phenomenon was exploited by the High Explosive Squash Head or HESH projectile. It is defeated by a number of methods including properly tempering steel plate so it is more ductile or using multiple layers of armor or sloping the armor.

[TranterUK]

Originally Posted by Teejay9

Tranter, would this be comparable to a "dum dum" bullet? I believe they were outlawed in WWI. Wouldn't that work just as well, if they flattened the front end? TJ

Dont know. Be interesting to find out though...