TechStuff Looks at Ballistics

Thank you. You know we did a podcast on nuclear weapons recently, Yes, we did, um, and right in the middle of it, for reasons that I can't even fathom, I started thinking about other kinds of weapons, and I thought, you know what, it would be kind of interesting to do a podcast on ballistics, which is basically the science of figuring out moving stuff and projectiles. Yeah, yeah, I I was. I agree, that was a cool idea. Yeah, it's a science of deals with motion of projectiles. But

of course it's been used. Sorry, I didn't mean an interrupt. I was gonna say that, you know, ballistics, it also is kind of shorthand for a specific branch of forensics, which is really what we're focusing on today. Yes, because when you get down to it, the actual study of ballistics is in large part a matter of physics. Yes. Yes, there's a lot of science involved in this. We know how we much we hate science, dad gum it um.

Unfortunately for the scientists, but fortunately for crime mystery writers. Bullets do not always behave themselves in terms of physics, Like, they generally go where they're supposed to go, but they don't always follow the normal path when they get there. Yeah, let's just say that it's all due to little, tiny individual differences on a very small scale. Because we don't mean to say that bullets somehow defy the laws of physics. No, but they don't always. They don't always travel like a

predictable path. Right. You might think, oh, well, if so and so was standing here and shot such and such over there, then the bullets should be right here. That's that's not always the case. Even even saying the cartridge for the the case for the cartridge should be right here, that's not always the case either. So to really understand this, first of all, we need to talk a little bit about how the forensics part of ballistics all came about

in the first place. Yes, and and really ballistics people have been trying to get the science behind uh forensics ballistics down for quite some time, but it hasn't really been that long that we really got it down pat.

I mean in the nineteenth century, Uh, there were people who were trying to figure out how to do this, but they were the methods they were using were not at all scientific, right, And to understand how you would be able to use ballistics to try and identify a weapon that fired a particular projectile, you have to understand a little bit more about what goes on with these projectiles.

So sometime around oh, the late fifteen century, the people who were creating firearms at that time discovered something which was that if you were to have a barrel of a weapon have some grooves in it to help direct the projectile to spin as it comes out of the barrel, you improve the stability of that projectile's flight path. Yeah. Previously they were what you call smooth bore, which was basically a a smooth tube. The inside of it was smooth, so you would, uh, you know, say, take your musket

and fire, uh, fire a shot from it. Um. Actually, you know this is this is I was getting ready to dismiss this in my head, but I think we should mention this. Um. You know those early muskets where you would you know, uh, you'd have to get everything ready. You'd have to put the wadding and the and the powder in and then the musket ball and tamp it all down with the rod before you could fire the weapon. You know, whether it's matchlock or flint lock, which we

talked about in another podcast. Um, but you have a basically a roundsh ball made of lead which is fired using um, the explosive gunpowder and the the gases propelled the ball out of the tube and you know they go, well, they go where they go generally go in the direction

that the barrel was pointing. Yes, more specific than that, Yeah, it h They weren't nearly as accurate as a rifled barrel, which is what which is what Jonathan was just talking about, where the there are grooves inside the barrel and they are UM and they travel in a spiral pattern. I remember correctly, didn't we talk about something in the rim when they started grooving the barrel? But they weren't They

weren't in a spiral pattern. They were straight m may have been I can't remember, I'm sorry, But eventually they did hit onto the fact that a helical groove spiral groove would uh where where that would create enough spend so that the projectile would become much more stable. Of like, this is the same sort of idea you get when you have a football player throwing a football American football.

American football player, um your hands. You know when you hear about like when you hear about like a tight spiral that helps that projectile in this case the American football maintain a precise flight path. Well, while that was very useful in making firearms more accurate, it was not the out of as a way of identifying a firearm based upon a projectile that had been fired for several centuries. It wasn't until the eighteen hundreds and uh actually I

have the earliest this. This is all from a website called Firearms I d and it was created by a guy named Scott Doyle who did some amazing research on ballistics, the history of it, and all of the elements that go into identifying firearms. If you are interested in the subject, I recommend you check out firearms, I d because it is truly exhaustive. I'm only going to give a small

fraction of what he made available. So the earliest of it, he found the earliest documented case of identifying a firearm UH in a criminal case happened in eighteen thirty five in London. And what had happened was a homeowner was killed by by a gun and a servant was suspected of being the perpetrator. And UH, a fellow named Henry Goddard UM who was with the London Police or with a branch of the London Police, was assigned the case.

And he examined the the the projectile that killed this shop owner and determined that it was made by a particular mold um by UH, which meant that it came from a specific company. And then he looked at the paper patch that was used in the the the firing as well. Now, this paper what it did was it created a seal between the powder and the projectile so that when the powdering knights and the gases expand, the projectile would have a good seal on it, so it

would it would fly out properly. And you saw that this paper patch had been made from some newspaper that had been in the room. He actually found the page where the newspaper had been torn to make that patch, and so they were able to determine that it was, in fact the servant who appeared to have fired on this shop owner. And so that was the first case.

Now in that case, it wasn't an idea, you know, specifically checking the bullet for the spiral marks that would indicate, um, what gone fired it, because that's that's something else we should mention, these rifling marks. Uh. In fact, that's why we call it a rifle. There's these rifling marks that are on the bullet itself. That's that's caused. As a bullet travels down this this grooved barrel, it cards little scratches into the bullet. And so these scratches are unique

to a particular weapon. Even even two weapons of the same make and model will produce different scratches, at least on a on a tiny let. You know, beyond a superfluous glance, you'll be able to see that there are different prances, and so it's almost like a fingerprint. If you are able to see, you know, tell that two different bullets are close enough and identity that these these markings are really really you know, to all intentsive purposes, identical.

You can say that they were both fired by the same weapon. So if you happen to have that weapon in your possession and you've done a bunch of test firings and all the bullets are coming out the same way and they matched the bullet that was used in a crime, you can feel pretty confident saying that that, in fact was the weapon that was used in that crime. Um. So yeah, I mean there, um, there are many cases in which you know, this has been this has been used.

I mean one of the first I read, and I read an excellent article by Katherine Ramsland um in uh in which he was talking about do you remember learning about Sacco and Vanzetti in your American history class? This very controversial, absolutely absolutely. Um. This was a case in which, uh, um, the payroll was being delivered to a shoe factory and a a couple of guys came up and shot the guards, and um, you know, they basically made off with the money,

and uh so they started looking for information. This, by the way, was April fifty, um, and this is when they started looking. Uh. This really was the incident that made modern ballistics a science, I think, UM, just from from the way they handled it. So UM, the investigators behind this UH collected all the evidence they could, including the spent shell casings. UM. They went back to looking

at the manufacturers of of weapons. UM. There were about six at the time that they looked at, and UH they turned out to be Remington, Winchester, and Peters UM that that could use these these casings UM. And what they what they ended up doing was they started, uh, you know, looking around at you know, what they could

get from this information. And as it turns out, one of the incriminating factors was the fact that for one of the weapons that they had, the only bullets that they could find, uh that would fit that weapon were in Saco's pocket. UM, which is pretty incriminating evidence, but it's not exactly that's circumstantial, you know. UM. So what they did was they talked to somebody who had worked

with UH sort of preliminary ballistics technology. His name was Albert H. Hamilton's and UH he actually had been um working with UH with other cases and UH he wasn't completely scientific um in his methods, but he he actually

got stuck in the middle of the case. And during this uh the Sacco and Vanzettie case, UM came in with new weapons that were UH similar to the ones that they had and basically disassembled them in front of the judge who noticed that he was swapping parts with the other gun and went, no, you can't do that, and they threw it out. But they did give the information to Calvin Goddard, someone who is quite famous in

ballistics forensics. Yeah, he's he's I would argue that he's probably considered by many people to be the father of this technology. He worked with a guy named Charles Waite at in New York with the Bureau of Forensic Ballistics, and he was using microscopes and a helixometer, which is a probe that you could use to look at gun barrels UM. I imagine that was used in the manufacturing

of these weapons. UM. But what he did was he fired these the weapons used or or in Sacco and Vanzetti's possession, UM into a wad of cotton and compared the casing and the bullet to the ones recovered in the investigation. And they were similar enough UM to incriminate

both of them. Now um, Vanzetti, I mean, they put both of them to death, but Vanzetti said he was innocent, and uh apparently Zacho's uh last words were long live anarchy, which doesn't exactly uh he he doesn't exactly say, well, you know, I didn't do any of that, but yeah, and and in later years too, they've still they continue to examine that and uh, right now, although it's still controversial whether or not these guys were railroaded or whether

or not they actually did commit the crime. Um, uh, they still say that. Uh, the weapons still support Goddard's findings even years later. So the technology we're using now

suggest that those weapons were the ones used them. That Bureau of Forensic Ballistics was formed in in April nineteen twenty five in New York City, and the whole purpose behind it was that by nine you remember, back in eighteen thirty five, was the first time we see someone trying to identify a firearm, uh, after a crime has happened.

The firearm itself was the one that was used. By ninety five, there had been a lot of pioneers who worked on this idea of identifying firearms based upon the projectiles they fired, and uh, The problem was that the the resources were scattered, right. I mean you had you had some communities that might have an expert that resides within that community, but then you know, you might have hundreds of miles of area where there is no expert,

there's no one to call upon. And so the Bureau was formed as a resource for law enforcement agencies across the United States. There were other countries that were doing similar things. Actually, a lot of this early research where the idea was, hey, look, they're these markings on this bullet. They're consistent with every bullet that's fired from this particular gun, and they're different from all the ones that are fired from that gun. That kind of work was being done

all over the world. In fact, there were a lot of people in France who wrote a lot of instrumental early papers on identifying firearms based upon their projectiles or Yeah. And then two, the FBI, the Federal Bureau of Investigation here in the United States was directed by a their jaunty head of staff, Jagger Hoover. I think that's the first time I've ever heard is I think that's what

Jay stands for, right, John T. Edgar Hoover. Um, No, not at all, uh, he know, it was more like, really you said that, really it was a question mark, like the sarcastic kind. It wasn't actually an interrobang, gotcha. So he directed that the FBI should create a lab for ballistics forensics as well, and so this was becoming really serious business. And then we're there were a lot of early cases between you know, the late eighteen hundreds and and nineteen twenty that established that this was a

legitimate means of investigation. So let's talk a little bit more about what you actually do when you're trying to identify whether or not a particular bullet was fired from a particular gun. First of all, it helps if we if we talk about bullets and cartridges because we and we've done this in another podcast, but it always helps because a lot of I think people who are generally unfamiliar with guns don't know the anatomy of a gun. Yep.

And that's part of why I wanted to mention that about the muskets Um because you know, after a while they realized that the system that we're about to talk about, it makes the weapons much more reliable using those things and faster to operate because rather than having to put the powder in the in the wadding and all that stuff in there, and and prepare the weapon to be fired. I mean, I saw I can't even remember what show

it was. I saw a thing on TV where they had somebody firing and must get as fast as they could, just to see how quickly a trained um musketeer could fire a weapon. It's about three times per minute. Three times per minute is considered an excellent time. Yeah, I know, I've seen I've seen artillery cruise that we're using, uh period cannon's um Actually it wasn't a cannon, but anyway, it was. It was an artillery gun, period artillery gun.

And they talked about how even with a well trained group of troops who were familiar with the weapon, three times a minute was considered to be the peak performance. So one of the biggest innovations was the idea of why don't we take the system of gunpowder and wadding and shot and all that, and why don't we try and figure out a way of packaging it all into one thing that you load into a gun once and

then you fire. So instead of having to load in all these separate pieces and pack them together and hope that it fires correctly. It's all packaged together there, and that's the idea behind the cartridge. In fact, the earliest cartridges were these little paper cartridges that had everything packed together, and uh, they were used in the Civil War mainly. But then actually that was sort of the step between where you put the cartridge in and then and then

the musket ball right right the shot. Yeah, the cartridge contained essentially all the stuff that you would have put in previously besides the shot itself. Well, the modern day cartridges have the the fuel that's going to push the the bullet forward and the bullet itself all packed together. So you've got a case that's typically made out of something like brass or maybe steel, depends on the particular manufacturer, and the ammunition involved pretty typically brass, and then you

have a bullet at the end. The bullet is the actual projectile that will fire out of the gun. The case remains behind. Now, the case also contains it contains powder, primer and a primer mix and uh, and that's the stuff that when a firing pin from the weapon hits the primer, that ignites the primer, which then in turn ignites the powder which creates this massive amount of gas. Massive in a relative term, I should say um amount of gas within the case. That's what pushes that that

bullet out of the weapon. So the case remains behind. The case is actually altered by this because the gases are pretty hot. Then they pushed pretty hard, so the case itself will change a little bit. Then you have to extract the case from the weapon and put a new cartridge in its place in the chamber of the weapon in order to fire it again. And of course

we've also talked about machine guns. So if you're talking about an automatic weapon, you put in you have a magazine, some feeding mechanism, feeding mechanism that will automatically pop the next it will pop the spent cartridge out of the weapon and uh load the next cartridge in and ready to be fired. And it happens very very quickly. So but it operates on the same same principle. So here's

the interesting thing, a couple of interesting things. First of all, we talked about the rifling with the grooves within the barrel which are going to cut into the bullet, making a fingerprint on that bullet, so that if you were to find two bullets fired by the same gun, and you were to compare them side by side, you should be able to see the same markings on both because it's it's going to carve it out the same way. Well, the same sort of thing goes plays for the cartridge

or like the case, rather for the cartridge. Um, the case, the spent cartridge is going to have some markings on it as well. Um, some of it maybe scratches just from you know, the way that it sits in the chamber, or if the there if there's an extractor, if there's an actual mechanical element in there that kicks that spent cartridge out, that can leave a mark on the case as well. So that way, if you don't maybe you don't even have the bullets, maybe you just have the

spit cases, you can compare those and see. So I Step one of identifying the weapon is identifying what caliber of bullet was used and you know what kind of cartridge was used, because that will limit the type of weapons that could have fired that particular ammo, right, because not every gun fires every immunition. Because anyone who has ever worked with guns nose they're very specific kinds of ammo that work with particular guns and you cannot you

cannot interchange them. Nope, nope. UM. And uh you know each each weapon Now, each manufacturer when they make when they put the grooves in there and the the section between. UM. Basically the ridges around the grooves are called lands. UM. Those metal ridges basically are what helped the bullet reach its destination by providing it the spin and accuracy. UM. But they also are are uh common to manufacturers. So one weapons manufacturer might put six grooves in the barrel,

one might use four. UM. So one of the things these marks left and they are unique to every weapon. UM. These marks are going to help the forensics investigator if if if they can find the bullets, they're going to be able to identify which manufacturer made the gun. That will help track it down. And then from there they can look at other things that will help them at least narrow down. He said, well, this couldn't have been uh, this couldn't have been the gun that fired because it's

not even the same manufacturer. It's not the right people. So we can rule this out. From there, they can look at specific guns because multiple manufacturers can make the same type of gun. Yes, so yeah, so narrowing it down to your First you look at the caliber of the bullet, uh and the case so that you can

determine what kind of m O was used. That narrows it down to a range of weapons that might be able to fire that looking at the actual pattern on the bullet itself and uh, well we'll give you at least an idea of the specific type of weapon used and the manufacturer. And then again comparing that bullet with one like a test bullet fired from a weapon will let you know if it's fired from the same weapon. So you're you keep narrowing it down. This is very scientific.

I mean you're talking about going from the general to the very specific, and so you're just eliminating all the other options until what you're left with is the only, hopefully the only uh possible answer. And um, there are a lot of different ways that that these the cartridges can have marks on. Besides the ejection UM mark, there could be firing pen marks, so you can see how the firing pin struck the bottom of the cartridge. That will tell you a lot about the type of weapon.

Like there's certain weapons that have a very distinct firing pen mark, So like a square one a good indicator that that was a glock that fired the weapon. And there are certain marks that are you're going to find that are common to particular types of weapons, So forensics experts will use that when they're actually examining UM bullets. So let's let's say there's a there's a crime case.

Let's make this more specific, there's a crime case in which someone was shot UM and the police have recovered a weapon from a suspect. They do not know if the weapon is the one that was used in the crime. They do know that it matches the same UM model and maker of the weapon that was used in the crime. But that's all I know. The forensics expert what they will do is they'll take the gun. Uh, They'll take possession of the gun that's from the suspect, and they'll

fire it into a water tank. And the water tank is a long tank of water several and it's usually around ten feet long. It's got about three ft wide three ft high full of water. And on one end of this water tank, which is sealed on all sides, which is important you don't want any stray bullets flying out, there's a hole through one side a tube where you can fire through that tube, it goes into the water. The water is meant to slow down the progress of the bullet, and as it slows down, it'll come to

arrest at the bottom of the tank. You the forensics expert will retrieve that bullet, and then they take that bullet and the bullet used in the crime, assuming they've recovered a bullet, because otherwise there's no point in doing this. So they've recovered a bullet from the crime itself. You put that and the test bullet or several test bullets into a macroscope, a comparison macro scope, and you might think, hey, Jonathan,

what's a macroscope, I've heard of microscopes. Well, macroscope is it's it's a device that does magnify things, but it usually magnifies them by a pretty small multiplier compared to a microscope. You know, microscopes you're talking about multiplying magnifying something by a hundred times or more. Macroscopes tend to be five, ten, maybe twenty times, so it's not it's not giving you that incredibly up close look that a microscope would. It's called a comparison macroscope because you can

actually put in two different items. So in this case, you put the bullet from the crime and the bullet from the test, uh onto the little platform it actually and here's there with some sticky stuff some some you know, it's essentially glue, um, and then you put it through

the microscope. The microscope directs the images up to the viewfinder where you look in and you can actually see side by side the two projectiles, so it looks like it looks like they are you know, right next to each other, even though they're actually on two different little platforms on the macroscope itself, and it allows you to take a really close could compare those markings at a a nice magnified level to determine whether or not they

are identical, or whether or not the markings are identical. Obviously, the bullets can't be yeah, because someone is probably saying, yeah, but Jonathan, why do they have to fire it into a water tank? I mean, why couldn't they just you know, uh, go to the crime scene and shoot it off the wall and see what happens. Well for one thing, of course, again you don't want stray bullets. But um, you know, I don't know if any if a lot of people know that. I mean it probably his common sense when

you think about it. But bullets the forms quite a bit in the process of firing them. UM. Actually, I remember UH my rifle recourse at camp when I was a kid. UM. Every once in a while, UH, the instructor would take us down to the end of the range and there was a big pile of dirt there. So the bullets would go through the targets and hit the dirt and stopped there. So we would go in and dig some of them out and they would come

out in the oddest shapes. The thing is, UM, you want the bullet to be identifiable enough so that you can really see the markings on it. UM. And shooting it against something else that will catch it. UH. You know, it will also be deformed by the impact if the water slows it down and it basically just drops to the bottom of the tank. Once it it's more forward

momentum stops. UM, then it's going to be much less affected by the impact of of uh its landing and UM then you can get a good idea of what it's actually going to look like in the marks that are on it and and sometimes the bullets retrieved from crime scenes are in really bad shape. I mean because they've they've gone through various materials, especially if you know they maybe hit like a door frame or something or

you know whatever. Uh, And it can be a challenge to identify them just because the bullets themselves may not be indecent enough shape for you to be able to make a good comparison. But this is to try and make the the conditions as ideal as possible so that

you can at least narrow things down. You know, the goal really is to see if you can eliminate that gun from suspicion, because if you can, then you know you're on the wrong track and you can go direct your attention elsewhere and not waste time on something that ultimately is a dead end. So um yeah, I mean that's that's your basic approach. It's kind of interesting, like the whole process of developing this. I mean, there were there were earlier UH forensics experts who would compare bullets.

They didn't have the luxury of a comparison macroscope to use, so in many cases they were using photography. They would take um pictures of these bullets and try and enlarge the photographs as large as they could and compare them that way, and try and find as many points of comparison as they could between the two to determine whether or not a bullet was in fact fired by the

same weapon as another bullet. So again, points of comparison, just like with fingerprints, you know, you look for a certain number, and if you you figure that if you find now uh like a dozen or two dozen points of comparison that are identical, the chances of that being just coincidence are pretty slim. So that's when you sit there and say, no, I'm pretty sure this bullet was fired by the same gun as the one that I tested.

And another thing that that Goddard did along with his partner, um, back in the very early days of all this, he started they started compiling a database of information about different weapons UM, which is, if you think about it, rather crucial uh to doing this because it allows you to know you know in which direction and which angle a particular manufacturers uh lands are going to show up inside

the barrel. UM helps you eliminate you know, they can look at a bullet and go, oh, well, I know that it's not this or this or this or this, and by the scientific method, I've at least narrowed it down to one manufacturer and from there, you know, and and having all that information in a database and comparing the weapons and I'm sorry, the bullets side by side, it gives you, um the ability to scientifically rule things

out step by step. And he really created a method and a plan for doing this that set the stage for what we know as modern ballistics work. Yeah, and it's if you read about again, I do urge you to check out more information about the progression of of keep gathering this information because it goes beyond just comparing bullets to each other. The history of forensics is pretty fascinating and in some ways sometimes darkly humorous and in

some cases just bizarre. Like you'll you'll find out about people sheriffs who found a victim who had um a hole in their shirt and there was suspicion that perhaps a a gun had the person had been shot by a gun and then a bullet had toward the whole. So the sheriff would take the shirt out to a firing range and fire bullets into it to see if the tears that were made by the bullets were similar. To the one that was on the shirt in the

first place. Well, they can tell um whether a wound is an entrance wound or an exit wound somewhat by the the type of hole that it leaves. I mean, if you're um, right on top of somebody, uh, it will um do more damage. If you're firing at somebody at point blank range. Um, then if you are farther away. But you can tell by the direction of the fabric, you know, if it if it's going into the wound, then you could see uh generally that it's probably an

entrance wound. And if the fibers are are spreading outward, then it's probably. And it depends on the bullet too. Of course, there are bullets that do a lot more damage on on one side or another, so that that factors into it too. Of course they'll talk about things

like blood spatter. Um. I have a great story here, I want to I want to tell them so all right, So in uh in nineteen o three, a fellow named E. J. Churchill in London, England, provided testimony uh do testimony that regarded an experiment he had performed that involved shooting bullets into sheep's skulls. Yeah, so skulls of sheep, not actual sheep. At this point that the sheep have already shuffled off

the wooly mortal coil and their skulls have remained. And what had happened was, um, it was all revolving around a case where there was a young woman who or a woman, I don't know if she was young, actually a woman who was shot and killed in Essex, England, and uh, they figured that she had been shot by a thirty two caliber revolver, and so Churchill took a similar revolver with the same sort of ammunition and a whole bunch of sheep skulls and started shooting the sheep

skulls at various distances to determine to kind of compare the damage done, to see how far away the shooter might have been from the victim by observing, you know, the damage done to the sheep skulls, and he came to the conclusion that the the revolver was shot somewhere between six and twelve inches away from the victim, and this was used. This testimony was used in the court case. In fact, the the accused suspect was found guilty and

put to death. So the experiments early on were very practical, you know, the idea of we have this one set of circumstances, we need to try and recreate it as closely as possible to to deter whether or not the scenario we have in our mind is actually at all accurate. And uh, and you know, like I said, the history of forensics is filled with stories that make that one seem tame and boring in comparison. Well, and and there are others that are oddly similar, um, that make you

realize that it isn't always exact because um. Ramslin mentioned a case that happened in Oklahoma where a robber used a three seven magnum and uh, there was a witness and he shot her right in the head. I'm just sorry, um. And uh what happened was the bullet went into her skull, but it traveled around the inside of her skull before leaving, and she ended up surviving and testifying against the robber.

On In another case, Uh, somebody got shot in the wrist with a twenty two, which is a much smaller caliber bullet um, and the bullet went into a vein, traveled into the heart and killed the persons don't always do well. And I also think I've even heard of people getting shot in the head and the bullet hits the skull and doesn't penetrate the skull, but rather goes underneath the skin, travels around the skull, and pops out

the other side without actually penetrating the skull itself. I remember, I distinctly remember when I was living in North Carolina, a police dog getting shot in the head and that happening. It's yeah, uh, yeah, this is getting really much more gruesome than I had intended. You don't mean, I don't mean for it to be gruesome, but I think it's

a situation. Well, I mean, the dog, the dog lives. Um, it's a it's a situation that shows you that, you know, we sort of assume that if you get shot, if you get shot in the right place and at the bright distance, that you know, they're a few chances that you're gonna make it if somebody's doing what they're supposed to be or what they intend to do, let's say,

with the weapon. Um. But bullets don't always behave themselves, which is why these ballistic forensics are so important because they you know, they've gotten it down to a science, so at least you have a better idea of what's going on. And we should also point out that that this, you know, we've been talking a lot about bullets. Uh, the story is completely different if you were to talk about things like shotguns. They do not have the rifled barrels.

So I mean you're firing shot at that point, not not a little lots of little balls. Usually occasionally you might have a slug shot slug, but at any rate, yeah, taser's yeah, totally different story there. But in those cases it's that you have to look for different things. You can't you know, obviously you can't compare bullets like you could with rifled weapons. Um. And in fact, Scott Doyle on his site rights, it should be noted that not

all firearms lead consistent, reproducible marks. But overall, there's been my experience that around eighty percent of the firearms that I examine produce what is sometimes called a mechanical fingerprint on the bullets and cartridge cases that pass through them.

So it is possible even for you to get a gun that, through some reason or another, Uh, the marks that come out the end up on the bullets and the cartridges are not I'm not reproducible, and it could just be that there's, you know, some sort of weird faulty part of that gun. You know, it's there's a lot of different factors that could that could cause that. And in those cases, of course, then you can't you know, the ballistics evidence as far as comparing bullets to each

other is no longer really reliable. You have to rely on other kinds of evidence in in that uh, in that sort of case, I would be interesting to know if any UH law enforcement authorities who have worked with forensics and ballistics have are listening to our show, you know, so please let us know if you you are, because this is interesting stuff, and thank you for the work that you do because it makes a difference. Yeah, we had some helicopter pilots right in after we did our

helicopter episode, which was kind of cool. No one offered to take me on a trip. It's not a it's not criticism, it's just a statement of fact. I think he's hinting, even after I said distinctly that that's on my bucket list anyway. What I have not had my cheerios this morning all right, so we're gonna wrap this discussion up anyway. Yeah, that's It's a pretty fascinating form

of of of forensics, a scientific inquiry really. Um, I found it very interesting when I was reading up on it, and like I said, the history in particular I found fascinating. If you guys have any subjects you would like us to tackle in future episodes, you can let us know on Facebook or Twitter are handled. There is text stuff H s W or you can shoot us an email at the address tech stuff at Discovery dot com and Chris and I will talk to you again really soon.

Be sure to check out our new video podcast, Stuff from the Future. Join how Stuff Work staff as we explore the most promising and perplexing possibilities of tomorrow. The hou stepp Works iPhone app has arrived. Download it today on iTunes, brought to you by the reinvented two thousand twelve camera. It's ready, are you