Home Forums Hunting & Shooting Ask The Gunwriters Bullet penetration in steel, comparisons...?

My 30-378 Weatherby used to shoot through plate steel like a knife through hot butter.

$bob$

varmit bullets dont punch through steel plate as much as they melt their way through...........


question....how well do you guys think zinc plates will hold up to firing? ive got some of those around that are about perfet target sized.....not very thick though....maybe 1/8 inch maybe ill haul one out to the country this weekend for grins

lots of info here. Check out the 5.56 vs 7.62 section.
Ammo info

In passing through steel, bullets do indeed melt their way through. Ackley did a series of experiments, and some of his small caliber, very hot rounds penetrated quite well.

Given that, you can apply basic physics. You have to convert enough of the kinetic energy of the bullet into heat, in order to melt the hole. So bullet KE is very important. More KE provides more energy, and will melt more metal.

If the bullet is smaller, all other factors equal, then less metal has to be melted to make a hole.

The key is lots of KE in proportion to the diameter of hole you want to make.

I do agree with your statement, but I had this happen to me several years ago. A friend and I were shooting several different calibers at pepper poppers between 75-100 yards away. He shot several rounds of .308 and .223 at the poppers. We wedged the hings so the poppers would not fall. Both of the above rounds left small dents but we could not get them to penetrate the steel poppers. I then shot the same popper with a 45-70 using a 300JHP Remington bullet at 2,500fps. This round went right through the popper. I shot several rounds and each went through the popper. I also tried several hard cast bullets in .45-70 and I couldn't get any of them to pass through the steel popper. I'm not a physics major, but I decided that the 300grain bullet passed through because of velocity and weight, wich must have created a lot of heat upon impact.

Our Silhouette Range bans 22 Centerfires and Magnums. I've seen targets barely dented by a 7 mag but had holes in them from a 22-250. Anything with high enough velocity will get you to rewelding the holes in the targets. The big boomers won't knock holes in them like a 22 centerfire but they will bend them to where they won't stay on the target stands. Using either on the Silhouettes will get the match directors pretty testy.........................DJ

Had to prep a big pile of 14" x 14" baseplates, for a steel silo once. Plan was to bolt the imbeds to the plates, fit 'em into the Sonotubes, and than swim grout them for load bearing final spec. ( this is WAY easier that trying to get imbeds all square, and fit pre-prepped bases)

Bid against the local machine shop, and as I was already in as a welding and steelhangin' contractor, I got the job.

Smokin'....130Gr hunting bullets, .270 Win did the job hansomely, at probably too close a range.........but you talk about clean holes......opening then up with the "Blue Drill" ( oxy torch) afterwards was a cakewalk.....it's the pre-heat and initial piercing that's so time and fuel consuming......so actually made a buck,on that one, and had fun, so doin'.

so,........130grainers at smokin' 270 win. vel....woiks.

This was a common A-36 grade steel 1/2" plate, by the way....not armor.

GTC

A bullet does not need to melt through steel. Machine shops punch holes more efficiently. I'm not sure there is enough kinetic energy to convert to caloric heat via friction to melt a hole.

The observation of what looks like a burned hole is probably a heat burnished sheared edge. I have read however about anti-tank rounds that create so much heat that vaporized metal kills the tank occupants. Not sure, I'd like to see the math.

When I shot my 7mm-08 into the plate, I had it tied to a large pine tree. The rounds that went through were stopped by the bark and were easy to pick up off the ground beneath the plate. They were perfectly sheared plugs- that didn't fit the holes they came out of!!!

I forget the exact science of it but metal plates have plugs and basically when the bullet hits it the plug slips therefore actually not penetrating it, but causing the distinct hole. Esox357.

I remember reading that, but I think those rounds used depleted uranium, or something similar, for the cores.

Tim

Yeah, depleted uranium in a projectile with huge mass and ultra velocity going thru several inches of tough steel designed to resist penetration (shear).

I see heat as the waste product of a primary event or action - and when kinetic energy is converted there is always loss. It can't be converted completely to the heat form.

Sure, heat is present but I suspect it is a byproduct and not high enough to melt a caliber size hole. Remember, we're talking about bullet against relatively thin plate.

Say a bullet travels with 2000 ft-lbs kinetic. This can be converted to 100% caloric energy with a multiplier (too lazy to get my conversion table) I don't think it would be too hard to get an idea of how many calories it would take to melt a hole.

I'm thinking you find out first how much electrical energy it would take to melt a hole (virtually instantly) and convert that mathematically to ft-lbs. Intuitively my reaction is that rifle bullets don't have the energy equivalent. I could be wrong.

Heat was definitely a factor in the craters made in my one inch plate.

Does everyone remember the famous photo of the milk drop hitting the surface of a jug of milk. The stop motion photograph portrayed a perfect crown of droplets from the impact.

That is what the impact craters of my 165 BT's on one inch plate looked like. Little crowns of melted and resolidified steel.

The order of events when a bullet strikes metal is always swage, shear then heat. That�s the way a bullet attacks every time � and that is the ordered way the bullet responds to the collision - mushroom � break apart�..melt.

How far a bullet gets into that sequence depends on what both bullet and target are made of and how much energy is present. All of this is the reason for the different observations of the event. Every collision has its own unique dynamics and degrees of progress.

A bullet hits a metal plate. In the first nanosecond it�s swaging and being swaged � the bullet is just trying to push the metal out of its way. The waste of that dynamic is friction or heat. What you see is a dimple in the metal and if you run to the target you may feel warmth at the spot. The bullet had deflected or simply dropped to the ground exhausted.

If the metal can�t be pushed out of the way easily or fast enough and there is still kinetic energy left to dissipate, the impulse forces break the metal by pulling it apart and/or shearing it. Once again the byproduct (waste) is friction or heat.

If the metal can�t easily be swaged and sheared because it is too tough, thick or hard and there is still energy left to dissipate that can�t be deflected � you�ve dimpled and torn the steel but the bullet is still come�n cause you�ve loaded hot, plus the bullet is tough and hard itself. Then you finally get the meltdown but only because there was not other way for the energy to dissipate at such a high rate of exchange.

I tried to figure how much more energy it takes for a 308 to penetrate like a 22 all else being equal. But there are too many variables and conditions are never equal. Maybe 30% more energy � not velocity � energy.

Oh, I stayed at an engineering school once. IIRC there were some guys there that could melt steel with their minds.

Hey wait a minute, doesn't lead and copper melt before steel. And didn't we learn from Rosie that you can't melt steel.

What if the steel plate was moving at 2800 FPS and the bullet was stationary. I guess the steel melting theorists would opine that the kinetic energy of the steel would melt the bullet. I wonder if there would be a hole.

Dripping sarcasm, I note. How appropriate.

IF the bullet melted its way through the plate, it would start melting in the center of the hole where its meplat strikes first. The plugs that I picked up looked quite similar to those made by an ironworker when punching holes, albeit a little more mushroomed. Nope, It just has to overcome the strength of the steel, whether tensile/elastic or what have you.

If you happen to hit the same spot a few times in a reasonable space of time, you can work-harden the steel to the point where it will fail and allow and otherwise inadequate round to penetrate.

There was an article in PS one time where a guy used a hardened plate as a backer with great success until one day he happened to shoot a group that was virtually one hole- you guessed it, there was a perfect hole in the steel behind the target- my guess is the last bullet finally overcame the steel and punched right through.

Velocity indeed is important, but it is rather difficult to say it is the most important, since penetration is strongly dependant on the combination of factors (in ballistics), such as the material hardness, shape, heat-resistance, density and mass (besides velocity). For example, a pointed copper bullet will penetrate better than a pointed lead bullet, because of the copper's superior hardnesss & heat resistance compared to lead (assuming they both have the same mass & velocity). If they both have the same final output in energy (foot-pounds of force per E=(mV^2)/Constant), then one that will penetrate say a steel plate better will be the one with higher heat resistance, hardness and density. A good example, a good armor piercing round will have a tungsten-carbide core which is extremely hard and dense -- tungsten-carbide is rated 9.0 on the Moh's Hardness Scale, which is only exceeded by a diamond in terms of natural hardness. tungsten-carbide is also extremely heat resistant. It has the highest melting point among metals, which is why tungsten-core rounds are ideal for armor penetration.

A friend of mine has a couple of 3/4" (I think) plates on his range. Have made no conclusions, but i have noticed that TSXs leave a much deeper crater than any lead-core bullet I have tried.

John

This effect only occurs when the velocity of the projectile exceeds the speed of sound in both the projectile material and the target material, about 5000 fps with steel. The physics are then the same as liquid hitting liquid--at 5000 fps. The projectile does not go that fast, of course, but an internal "shaped charge" accelelerates a portion of the projectile to that speed upon impact. This effect has nothing to do with bullets penetrating steel.