physics question ??

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mike28w

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Hi !
Anyone out there who has a handle on physics ?

Question : If a person were to shoot a falling or tip over metal plate ( like an IDPA plate) with a 230 grain bullet and it rickocheted directly back at the shooter......how much energy ( or velocity) would it retain ?

I chose the 230 gr. 45 cal. bullet arbitrarily. Mostly because the velocity is well known. I understand that one would need to make a bunch of assumptions and generalizations..... but still it would interesting to at least have an idea.

I ask this, because , since I've had my electronic ear muffs....I have heard a bunch of rickochezs. A bunch ! I had no idea !

I have only seen one person who had been hit by a richochez of unknown size ....and it made just a superficial cut on the forehead. Not even close to needing stiches.

I'm hoping to hear from " Dr. Science" ( because he knows more than I do !!) :) mike
 
So take the speed there minus the loss of velocity, then calculate KE using the formula 1/2mv(sq). Then calculate the required energy required to knock over the plate and subtract it from the calculated KE. This will give you remaining KE. Assuming the bullet retained all it's mass reverse calculate the return velocity minus the loss for distance...
Real world, I've been hit with fragmented .22 rounds shooting indoor at 50ft, assuming they left the barrel at 1100fps they hit me moving very slow. A DIRECT ricochie back to the original shooter would be very rare. I have heard wizzers shooting outdoor silhouette from neighboring stations.
 
Unfortunately, that really can't be answered with any accuracy given the information provided. If you could measure the velocity of the projectile post-ricochet (assuming it lost no mass), then you could know. Otherwise, it would be a big guess.

The energy retained will be the kinetic energy of the round immediately prior to impact minus the sum of energy expended for deformation of the projectile and energy imparted into the plate. This is all dependent on the initial velocity, friction, angle of impact, type of round, etc.

On the note of ricochets and IDPA, we did have a night where the jackets from one shooter using .357 were ricocheting back into the crowd. The guy in front of me had his sleeve cut, and I took a hit - it had enough speed/energy to embed a fairly small piece of copper (1/4" or so) under my bottom lip.
 
If you spend much time at a Steel Plate match, you will be hit by a ricochet (note, the plural is ricochets, no "z").
Those plates do not fall. They probably move a little bit (albeit very little...they do not require re-setting between shooters).
The ricochet is usually a fragment, and is noticeable but not even annoying.

The club where I shoot insists that you keep glasses on whenever there is a shooter on the line, and I can see the wisdom of that edict.

Bottom line: unless you catch one directly in the eye (without safety glasses) don't worry about it.
 
I've had a piece of .45 get deeply embedded in my hand in this manner. It's still in there. Ditto one in my belly. Neiher fragment is bothering anything and both are embedded too deeply for an amateur to be cutting it out! :) This was at 7 yds, IIRC, 30 odd years ago. I also had a jacket from a 308 ball rd, same distance, get embedded in my arm so deeply that a pair of visegrips were needed to extract it. I was firing thru the window of the last barricade on a Cooper assault course, so I "thought" I would be ok. Big error.
 
Most bullets will flatten or fragment upon impact with a SMOOTH steel plate. Return ricochets are likely only if the plate is cratered or deeply dented. Even then, usually in fragments.
I have been hit hard enough by fragments to draw blood or leave a large bruise. The worst hit like a hard punch.

I once picked a jacket fragment out of my gunsmith's face. There have been some deeply imbedded pieces of bullet.

The only whole bullet I have been hit by was a .44 Special that bounced off a railroad tie, not a plate. Retained velocity was low, which was good because it hit me in the face.
 
You will not be able to figure it out unless you know the velocity it leaves the plate. I have been hit by a ricochet from a 45 colt and it hit me in the gut. I didn't penetrate but I was done shooting for the day Haha
 
+1
It is a question that cannot be answered due to?

* Velocity of the bullet?
* Thickness of the plate, and how much it deformed or 'sprung back' when the bullet hit it?
* Did the bullet hit a divot in the plate and focus the shrapnel straight back at the shooter?
* Etc, etc, etc.

I have also been hit from a bounce-back .45 Colt bullet off a railroad tie backstop.
It tore the heel off a good pair of boots, and nearly knocked me down.
It would undoubtly have resulted in a serious injury had it hit me higher up in a soft or vital spot!

rc
 
I don't know about IDPA, but I knew, past tense, a guy who shot a piece of steel with a 30-06 from about 50 or so yards, the projectile didn't go through, instead it came straight back and struck him in the head, killed him.

I shot at a 1/2" piece of steel with a 9mm 147 gr. JHP's from about 25 yds. and fragments came back and hit me in the leg.

GS
 
I was hit in the thigh by a .45acp ricochet from a target about 10 yards away. It felt like someone had flicked me (hard) with their finger. It didn't hurt but it did get my attention. I found the intact round (still warm) about two feet in front of me.

What I got out of that was that ricochets aren't a big deal if they hit you in the body, but make darned sure you're wearing eye protection.
 
A friend of mine has some steel animal silhouettes that we shoot at, and they are welded to a bottom plate so the target sits at about a 10 degree angle off vertical. Never been hit by a ricochet. Are the targets most people shoot at vertical when you experience a ricochet?
 
I use to teach radiation safety and physics for the army when I was active and based on your question there are too manny question left unanswered. Distance to target,make up of bullet , such as hp, fmj, etc, velocity of fired round, angle of target for trajectory of bullet round, so far MR. Ford8nr has given the correct formula but your question still cannot be answered, just guestimated at most since the coefficient of the bullet will change upon striking target creating more drag on its return trip.
 
I understand the vagueness of my question and appreciate all of the responses. I was hoping that someone would be willing to generalize (admittedly a bunch) and give me some ballpark figures.

I still think it would be helpful. Any brave soul that would like to attempt such an endevour would be welcome to use his parameters.....such as distance, velocity and bullet weight.
Anything would be helpful. As a suggestion, 45ACP, 230 FMJ, 800fps, 20 yards, steel target is perpendicular to bullet, no pits in steel target, you chose whether target falls or is stationary....any other variables....you are welcome to choose as you see fit.

As an afterthought, reading through these responses , I'm struck ( pun intended) by the wide variety of reports. Some barely feel an impact, while some feel a much stronger impact. I would be pleased if someone could state that in these circumstances that the energy would be 1-10% or 20-30% or some other representative number.....

Maybe I should suggest this to "Mythbusters"..... (it's fun to watch them blow things up !!)

Thanks ! mike
 
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There is a good reason for the variation in the reported effects of ricochets.

I asked this question, years ago, of one of my ordnance engineer colleagues. He stated that he could only answer my question if he were dealing with an infinitely hard and rigid projectile striking an infinitely hard and rigid backstop perpendicular to the incident of the strike.

In that case; the projectile would return directly in the direction of origin at the exact velocity it struck the backstop. The impulse imparted to the backstop would be equal to the energy of the projectile and the returning projectile (at that moment) would retain all the energy with which it struck the backstop. This is the equation for momentum: M=2xVMa where M=momentum, V=velocity and Ma= mass.

Note that momentum is not the equation for energy (E=MC^2) but it is moderately useful in predicting the force required to knock a silhouette down if you want know how to knock it off its stand and not just "rotate" it over.
 
Ive felt fragments hit me and seen fragments draw blood on a guys forehead. Also a personal account of a 22 ricochet off a rock striking another in the head and killed them. Be VERY careful when shooting steel.
 
mike28w, a civilian .45 ACP bullet striking a hard metal plate acts like a drop of water hitting a hard surface, rather than a rubber ball. The lead core of the bullet tends to "splash" into tiny fragments that spread radially from the point of impact. The copper jacket tends to hold together in large pieces but it is only a small part of the bullet's mass.

If the bullet hits a preexisting divot in the plate, then the "splash" can be redirected back toward the shooter, but it will not be a single mass. A jacket fragment might be similarly redirected, or might "bounce" off a springy piece of steel, but the effects are not easy to predict.

Go here and fast forward to 6:19 to see what I'm talking about. There are a lot of other fascinating slow-mo videos there of bullet impacts, including handgun bullets impacting glass, hunting-caliber rifle bullets impacting mild steel, and rifle bullets impacting hardened steel.

https://www.youtube.com/watch?v=QfDoQwIAaXg
 
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