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We killed the plate today

Discussion in 'General Gun Discussions' started by Jeff H, Jun 14, 2017.

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  1. Tommygunn

    Tommygunn Member

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    I meant in the bullet, which has kinetic energy. The metal plate only has potential energy, but that could only be realized if it were to fall to the ground, aND is irrelevant to this situation.
     
  2. denton

    denton Member

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    Light waves and radio waves do have mass. We have measured the deflection of starlight due to gravity, for example. That was done a long time ago.

    Elastic collisions follow the same rules as optics. Ping-pong balls fired at a parabolic surface will follow the same course as light rays.

    When a bullet strikes a steel plate, it's an inelastic collision. Momentum is conserved because, well momentum is always conserved...one of the great laws of physics. Ideally, momentum of the bullet before the collision becomes momentum of the plate as it falls.

    I did major in physics, but I can't say exactly what the mechanics are. Still, it is a demonstrated fact that as your plate rack gets more and more pock marked, you get more and more ricochets. The ricochet seems fairly often to be just the bullet jacket.

    The original assertion by denton was that the entire bullet would come back at you, not fragments.

    Not at all the intent of my statement. I said nothing about the entire bullet, and I did not specify a particular direction.
     
    Last edited: Jun 18, 2017
  3. tark

    tark Member

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    If you would actually read and think about what I am asserting you would realize that all I have claimed is that a 180 degree ricochet is not possible with any real degree of force. If you shoot at a range where hard objects are downrange that cause bullets to ricochet and land on the roof, you might want to change ranges. I have never been to any range, anywhere, that would allow a dangerous condition like that. I have been to ranges where you were shooting in the direction of a stone cliff but they had constructed sand box pits for the bullets to impact in.

    A coin came back and buried itself three inches into your leg? Well, for a bullet to turn itself into a "coin" it has to strike something very hard. Steel? My God, how close to the target were you? Must have been pretty close. If you knew how dangerous it is to shoot at hard targets.... well nevermind.

    Have you considered that those bullets on the roof might have been lying on or near the surface and been struck by the bullet heading down range, which transferred it's energy?

    The bullet has no kinetic energy left when it comes to a stop....
     
  4. tark

    tark Member

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    An excellent point, quite true. but when a bullet hits a pock mark it is not hitting a flat surface, it is hitting a mildly concave surface which deflects the nose of the bullet causing a ricochet, which is usually not dangerous. All I have maintained is that a bullet hitting a hard surface at a perfect 90 degree angle will not ricochet with any amount of force.
     
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  5. denton

    denton Member

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    "Usually" being the operative word.

    Our range did have a fellow catch a bullet fragment off a steel target frame with his liver. He required surgery.

    I've seen a ricochet off steel take out the rear window of a BMW at the range. (Shouldn't have parked where he did.)

    Hadn't thought of this previously, but when I was still a young guy, my cousin and I would try driving nails with a .22. When you hit the head, the bullet, or a chunk of it, frequently whizzed by our heads. We quit that.
     
  6. wally

    wally Member

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    Have you ever seen one of those desktop doohickeys with a line of steel balls hung on strings where you pull one on the end back and let it swing into the rest and low and behold it swings back the opposite way shortly thereafter close to the position you released it from? Its on a much shorter time scale and deflection distance but the physics is basically the same.


    Bullets that penetrate are never a problem, except for what might be behind the target, the first hit on a flat plate is only a problem for things at a shallow angle to the plane of the plate or at velocities not high enough to "splatter" the bullet (for example .22lr, by far my most common bounce-back). But when the plate is creatored a second hit in the creator can focus the splatter straight back at you with a serious fraction of the original energy, its an empirical fact, you can ignore it at your peril. Its all probabilities but you only have to loose once.

    I've been hit in the chest by a pellet fired from an air rifle that bounced straight back after hitting a tree.
     
  7. Big7

    Big7 Member

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    Bet? Bring it. Pink slips. If I lose, I'll fly you back.

    You lose, take me fishing around Miami or Homestead.

    Called out, on you now.
     
  8. RecoilRob

    RecoilRob Member

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    Regarding an armor piercing shell being able to rebound back toward you with significant velocity....somewhere I remember seeing up to 90% of impact is possible in such a case. This would apply to solid shot squaring up a surface that it cannot penetrate....as seen often on German tanks in museums where they'd gone up against Shermans early in the War. Whatever energy the shell had as it struck, minus that needed to deform the surface and nose of the shell....whatever is left will come back off and from the shallow divots I've seen, there were lots of rebounding Sherman shells flying back at them when they hit square and didn't angle off. Even very thick metal has elasticity and some 'give' to it when hit really hard.

    When we shoot steel with the 50, it's always important that you be able to either fully penetrate or stick the cores else you are in peril. I caught a 375 H&H in the leg that came back from about 80 yds that didn't make it through a 1" plate. It looked like an extruded lead ribbon and didn't hurt...but it was surprising nonetheless.
     
  9. Jeff H

    Jeff H Member

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    Go back and read the OP again. We've been trying to penetrate that 5/8" plate for a couple of years with regular rifle rounds.

    It is a mild steel plate, left over scrap from a fab shop. This is not a valuable AR 500 plate.
     
  10. tark

    tark Member

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    Uhhhh..... has it ever occurred to you that I might have tried that already? You're not the only person in the world that has a Mosin-Nagant and different types of 7.62X54 ammo. Nothing I tried did any better than M-80 Ball. I DID say that armor piercing 7.62X54 would no doubt do the job.
    Render one of the end balls immovable, then see if the thing still works. It doesn't . The thing works because all of the balls weigh the same and energy is transferred evenly. Replace any one of the balls with something heavier and it stops working.

    I have things to do today, back at you all this afternoon. Think I'll do a little shooting.
     
  11. fpgt72

    fpgt72 Member

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    This is totally different from my experience...

    My FiL Found some metal plates on the highway...and being the redneck he is grabbed them. About the same thickness, but a little pounded on...I guess they fell off a truck or something and bounced down the highway. Called Missouri Southern (that tells you how long ago it was) and they did not want them back....so I kept them.

    They are very heavy very thick, but not hard. In talking to people they don't want hard steel for rails and switch plates as they want it to move with the weight of the train....be a little bendy. Ever watch a train on the tracks and see how everything moves as it rolls by....too hard and they would crack.

    This steel I have is pretty worthless for shooting at, anything more then a pistol will poke holes in it.....I am talking a 30 carbine will crater it.

    AR500 steel is really tool steel....the AR is for abrasion resistant....used on things like the scoops for backhoe's doser blades....grader blades....stuff like that.
     
  12. tark

    tark Member

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    You sure you want to make that bet? Look at these pics, shot this morning. Ammo was Russian ball 148 gr, corrosive, green case. Copper washed case is more recent non corrosive 148 gr ball. Both bullets have steel cores. Note them sticking to the magnet. I decided to try the tests at 25 and 50 yards, because I already knew what could happen at 100; not much more than a dent. At 25 yards the green case ammo went first, this is hole number 1. I was surprised. It put a deep dent in the plate.....but it did not penetrate. Hole #2 is the copper washed ammo; nowhere near as good. 3 and 4 were at fifty yards. Still fairly deep dents, but nowhere near penetration The armor defeated the incoming rounds in each case except for hole #5, which was a .300 Win Mag 150 gr factory round.. Well.....that outcome was easy to predict.

    Before anybody starts, I had protective cover for the 25 yard shots, to preclude any howls of anguish about being too close.

    Big7, unless you have some secret, super powerful 7.62X54 ball ammo, you will lose your bet. Save yourself time, effort and money and back away from that bet.
     

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    Last edited: Jun 19, 2017
  13. Tommygunn

    Tommygunn Member

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    :scrutiny: *SIGH......* The bullet has kinetic energy when it leaves the gun's barrel. Ok? What happens to that energy upon impact with the steel plate may depend upon some qualities of the bullet, as well as the plate, and how the plate is being held. But the energy does not disappear, it does something that in physics is called "work."
    I trust that I have been sufficiently clear in this post that even Mr. Spock would be forced to agree.....:D
     
  14. tark

    tark Member

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    The bullet has no kinetic energy of motion left once it stops moving. It transfers that energy in whatever way to whatever it hits, but it has none left itself. An immobile object has NO kinetic energy of motion. It DOES have inertial energy of rest and will then resist attempts to move it. It enters this state the instant it stops moving.

    I agree with your post, the energy is not lost, it is transferred. A.K.A. "work"
     
  15. Sunray

    Sunray Member

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    .30 AP at 2800 fps was required to penetrate 7/8" of armour plate not less than 0.42". Mild steel is nothing. So is some AR500 plate.
    "...regularly gets pelted with .308..." But with hunting bullets, not AP. Ain't the same thing.
     
  16. DT Guy

    DT Guy Member

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    If this were true, a billiard ball couldn't bounce on asphalt.


    Larry
     
  17. Big7

    Big7 Member

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    No.. It will do the trick. And as stated, it IS steel core ball in my original post. Not AP..

    The oldest military ammo still in use.

    I'll still take the bet. Bring it.
     
  18. Tommygunn

    Tommygunn Member

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    If a ball bounces it still has kinetic energy and hasn't lost all of it to the ... "work" of hitting the asphalt.
     
  19. tark

    tark Member

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    Let me see if I have this right. You want me to drag my forty pound piece of armor plate onto a commercial airliner, bring it to Florida, let you shoot it with your ammo, which is probably the same as mine, What makes you think your ammo would do any better than mine?) and If I win you will fly me home?

    I would be an idiot to take that bet. For starters if I won, you would pay for the ROUND TRIP not just the ride home. And I can't see the airline not being suspicious over someone wanting to take an armor plate full of bullet holes on their plane. So that means it would have to be shipped. Round trip payment on that one, also.

    I am 69 and have diabetes, gout, hypertension, a bad back and one bad knee. I live alone, and if I left, someone would have to take care of my animals. (I live in the country) You're the youngster, you come to me and I'll pay YOUR plane fare if I lose. But that isn't fair for me ask that, I assume you are still working and would have to take time off. So you have issued a challenge that I cannot respond to. That means, by the rules of such activities......

    We will declare you the winner of the bet. :D Now we have to negotiate what it is that you won:eek: .
    I'm thinking the ball transfers energy to the asphalt, which transfers it back to the ball. All I can think of, anyway. Some energy is lost in all this shuffling around. You will notice the ball fell 50' but only rebounded 15 or 20'
     
  20. Big7

    Big7 Member

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    Deal.. I have the plate. And the round trip air. You get that and the guided hunting trip of your choice.

    WHEN you lose, I need a fishing trip to Miami / Homestead on your dime.

    I'm game. Are you?
     
  21. tark

    tark Member

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    Sorry but you are altering the conditions of the bet. The deal was your ammo couldn't penetrate MY plate. Which I am quite certain it can't. I proved that this morning. How do I know your plate is the same armor plate alloy as mine? Or if it is even real military armor plate at all? You can't change the rules in the middle of the game.

    Did you not read the third paragraph in my post.? I cannot accept the challenge in any case because of health and other reasons. I declared you the winner on a technicality. What more do you want? (No, you can't have the 1911 in the picture!)
     
  22. .308 Norma

    .308 Norma Member

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    http://blog.discoveryeducation.com/blog/2014/02/28/fun-fact-friday-bouncing-balls-rubber-vs-steel/

    This article isn’t about bouncing bullets, it’s about bouncing balls - rubber versus steel. But I don’t know why some of the same principles wouldn’t apply. Especially if we’re talking about very hard bullets, as compared to say, relatively soft, swaged lead bullets.
     
  23. 45_auto

    45_auto Member

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    I shoot at a lot of steel, but I won't shoot at cratered steel.

    Back in the late 1990's we had a couple of mild steel, severely cratered, 4 inch thick plates, 3 feet by 3 feet square hanging from chains on 6x6 frames at the 100 yard line. They looked like the surface of the moon.

    I decided to see if I could put a hole through one with a 30-06 Black Tip out of my Grand.

    The instant I pulled the trigger it felt like somebody hit me in the wrist with a sledgehammer. Knocked my arm straight out behind me. I thought the gun had blown up.

    The scar in the yellow circle (picture taken just now, 20 year old scar) in the picture of my right wrist (trigger hand) below is where the tungsten core entered my right wrist before traveling down the length of my arm and stopping in my elbow. It was about 1/4" in diameter, about 3/4" long, and bent into a "J" shape with the pointed end bent back all the way around. They used orthoscopic surgery through the entrance hole in my wrist to get the bullet out. A couple of inches higher and a couple of inches left it would have been in my eye. I doubt if the safety glasses would have stopped it. If it had come back on the left side of the gun instead of the right it would have been in my chest.

    We took the cratered plates down a few days later.

    [​IMG]
     
    Last edited: Jun 19, 2017
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  24. 9MMare

    9MMare Member

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    Wow, God bless!

    One can only wonder at what the moron was thinking that shot steel from 12 inches away....(and I guess felt the pic of his shrapnel wounds was 'educational' yet couldnt explain why he did it)
     
  25. Nuclear

    Nuclear Member

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    Depending on the construction, bullets can deform and spring back, like a rubber ball. Likewise, depending on construction, the target can compress and launch the bullets back. A classic physics question revolves around which impact deposits the most momentum to the target? The answer is where the incoming object bounces off the surface of the target, minus the energy it deposits moving the target.
     
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