I’m going throughold seasons of X-files and catching up on episodes I missed (damned strike). In one ep someone takes a shot at Scully in Mulder’s apartment, leaving a bullet in the wall and a neat hole in the glass, with some cob web lines tracing from that hole.
It’s a staple cliché in movies and tv, but wouldn’t a 9 mm bullet shatter part or all of the pane, leaving shards on the floor and some sharp pointy bits still hanging on to the frame?
No - it would go through it clean as a hot knife through butter.*
9mm are known as neighbor killers or something like that because the bullet goes through one wall of sheet rock into the next room, into the next, the next outside and hit’s a neighbor in his living room.
*the breaking of the glass cleanly I believe depends upon where you are when you fire it, what type of glass it is, the velocity of the bullet etc.etc. Someone will come around shortly with specifics I’m sure.
Maybe the writers are subscribing to the canard about glass being liquid, in which case a bullet would leave a neat little hole, which would then sloooooowly heal itself.
True Story:
When I was in college, some of my dorm mates built a SERIOUS sligshot. They used the bole of a tree as the “Y”. They used about forty feet of surgical rubber tubing as the elastic, and used a washcloth as the webbing to hold the shot – which was generally a water balloon. With one man each holding one side of the top of the “Y” against the sides of a window, and a third guy pulling the elastic well down the hallway, they could shoot water balloons out the window, across the street, and well into the next Block.
They had it down to an art. Filled water balloons were kept in a plastic garbage can filled with water, so that they were in neutral buoyancy, and wouldn’t break the bottom balloons with their weight. They could recharge and rerfire at a rapid pace, and with considerable accuracy.
One day, instead of firing at the next block, they decided to loose the full fury of the balloon slingshot at the closest window facing them. Not even across the street. So they loaded up a balloon, pyulled the rubber tubing ALL the way back, and let fly!
.
.
.
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It struck the window dead center. The window did not crack. It did not shatter. It had, punched into it, the round silhouette of the ballooon, as if a perfectly round Warner Brothers Cartoon creature had run through it. Or some cat burglar had used one of those glass circle cutters on it.
In my neighborhood last year, some yahoos took delight in shooting through the windows of random businesses late at night, including the office where I work. I’ve passed by at least 2-3 businesses along this street that still have fairly neat round bullet holes in their glass windows.
Another anecdotal occurence, the amusement park I worked at had a bullet come through a window and hit someone in the arcade. It only left a small hole with some cracking/spalling around it.
I suspect this only happens for plate glass windows. Safety or pre-stressed glass would shatter into a zillion little squares.
Well, since we’re talking anecdotes already, I’ve got one for ya. I used to work for a company that did explosives and munitions testing for the Man. Amongst other things, one of our test was a sled track that was powered by up to twenty rockets, propelling a projectile into several slabs of concrete, of varying thicknesses.
In order to track the pitch, a high speed camera was set up orthogonal to the flight path. To track the yaw, instead of setting up a camera above the test (those things are expensive), we would place a mirror at a 45 degree angle to the ground. If the mirror were to break, there would be too much dust and debris, and the projectile of interest would be past the mirrors by then anyway (it was going about Mach .85).
It would surprise me that the sleds would be destroyed (as in, unrecognizable), the walls wold have a two foot diameter hole in them, all the test stands would be mangled, and yet we were able to reuse the mirrors two times out of three.
A nurse once told me about a random bullet that “shattered” the glass door of a nursing home.
Damn. Why do some people get all the fun jobs?
In the window or in the person?
It was a student job on campus. I got about 10 of my friends jobs there, too, although most of them didn’t work there long enough to make it out of the carpenter shop. I spent about a year in there before I started working in the field.
That’s correct. Our intuitions have been spoiled by action movies, in which all glass (at least all glass that gets targeted by bullets) seems to be safety glass.
If a bullet hits a plate glass window fairly square it will leave a nice round hole of the calibre of said bullet. The hole will have a spall about 3 diameters of the hole for 1/4 in. glass,and twice the diameter for 1/8 in. If it hits at a sharp angle it’ll shatter the glass and leave large shards in the frame. If it hits tempered glass it will break into lots of little pieces the size of the thickness of the glass. And if it hits laminated it’ll leave a small hole a little larger than the calibre, and spiderweb the rest of that piece with chriscrossing runs but the glass will stay togeather. I am a glaizer.
From my experiences taking pot-shots at wrecked cars on rural farms, a centrefire rifle bullet fired through a car’s side windows from 50m will shatter most (about half) of the glass, depending where you hit it, and a .22 rifle bullet from 25m will leave a hole with a lot of starring/cracking radiating out from it.
I’m amazed. There truly is a Doper who can answer any kind o question.
Thank you.
Is it glazer, glaizer, or glazier, Glazer?
It also has a name. Hertzian cone, though that’s usually used for much smaller things like BBs I imagine it’s the same principal idea, just with lots more force.
I’ve frequently seen thick plate windows which have a small hole on the side struck, with a cone-shaped opening extending from there to the other side, so the hole in the opposite side was several times larger. Two of these wrere in my elementary school, which probably tells you something about the neighborhood I grew up in.
As a kid who’d read about Prehistoric Mamn, I recognized these conical fractures as Percussion Cones – as the sound wave proceeds forward through the glass, the waves spread out in a circle, and at the edge of the disturbance you get a fracture. Theoretically, the conical piece of glass falls off inside, but I’ve never seen one. Our ancesters used to use this method of percussion gracture to precisely chip flint (and they were looking for that part that fell off. The edge, if this is done properly, can be extremely sharp).
This is great!
Thanks.
Nothing like real experience to answer a question…
