What Degree of Specificity Can a Fired Bullet Reveal the Make and Model of the Gun it Came From?

[SwampWolf]

I watched a "true crime" tv show last night where the police were able to determine that a bullet recovered from a victim came from a Colt Python revolver. Is this possible? How could an analyst differentiate between a bullet fired from a Python from a host of other Colt revolvers chambered in .357 Magnum (or .38 Special for that matter)? Just wondering.

 

[GRIZ22]

Don't know about model but number, width, and depth of lands and groves can id make and caliber. These unique markings can also id a specific gun if you have a fired bullet and the gun.

 

[DrDeFab]

Some additional info here, if a little dated: https://www.firearmsid.com/A_nogunid.htm

And here are some recent developments in matching a bullet or case to a recovered firearm: https://www.nist.gov/news-events/ne...g-statistics-forensic-firearms-identification

 

[PistoleroWadcutterGANG]

Locard's Law of exchange. makes every projectile unique to the firearm. From the micro contact engraving from travel in the bore / rifling to the firing pin indentation. Even if altered mechanically to evade detection / identification, those alterations again play out the principle (for every contact there are trace / Identifiable characteristics. Now days data bases "Classifying" barrels, bullet composition, Manufacturing metals in the firearms industry are being compiled as we speak / type. Thanks god we have very smart people out there, willing to fight evil.

 

[eddiememphis]

Yes, it is possible.

Only if they have a gun to compare it to.

No way to see a bullet and go "Aha! That was fired out of a 1971 Colt Python."

There are certain characteristics imparted to the bullet by the rifling, if it is recoverable and intact enough to examine, that may be identifiable, but when the TV guy bends over and says it is a .357, that's nonsense.

Revolvers and semi-autos can both fire bullets sized .355 and .357. Without measuring the base it is very difficult to differentiate the two. Revolver bullets in .357 tend to be heavier which would make them longer.

To identify the gun used without being able to slug the bore and match it under microscopy is nonsense.

 

[sparkyv]

I watched an old Dragnet episode where the serial number of a specific fire arm was traced back from the bullet marks.

 

[Jim Watson]

The rifling plan, if not too damaged by impact, can identify the make and maybe the model of gun. Can, not will.
Claims of identifying individual guns by unique tool marks is a lot less likely than depicted or claimed; even if Mike Hammer did keep a supply of replacement barrels for use after he shot somebody he didn't want to be connected with.

There was a PD that had special order barrels rifled with identifying artifacts. I don't know if it was one standard for the whole department or individual to the issued pistol, though.

 

[Odd Job]

To match a bullet to a make and model of gun requires the gun to have barrel class characteristics that are unique OR it requires the ammunition that was found, to be uniquely usable in a certain model of gun only.
That's a tall order: I think it would have to be a manufacturer who produced only one model of gun, with unique rifling or equivalent features.

 

[rust collector]

@GunnyUSMC was involved in at least fired case analyses later in his career. He would be able to give classes on the subject.

 

[Jeff62]

https://www.scientificamerican.com/article/the-field-of-firearms-forensics-is-flawed/


Forensic science is evolving.

 

[sgt127]

Forensic labs, big ones, have guns or fired bullets to do comparisons against. That will get you in the general make and model of a fired projectile.

I went to Sub Gun instructors school at FWPD. I had my issue MP5. (And…2000 rounds. It was a good time)

While there, the director of the Tarrant County Forensics lab came by. In chatting with him, I mentioned we had three Jati machine guns.

He was really excited and asked if I could bring it the next day. He desperately wanted a few fired projectiles to keep in his comparative files.

I brought it. He took it to his shop, got his samples and brought it back. He wasn’t excited about shooting it. He just wanted the bullets that were fired in it.

The odds of him ever working a shooting involving a Jati were, astronomical. But, maybe in their world, it was bragging rights to have them.

Super nice guy. Passionate about his job.

 

[Double Naught Spy]

The odds of him ever working a shooting involving a Jati were, astronomical. But, maybe in their world, it was bragging rights to have them.

Well, while he may have enjoyed having the bragging rights to a unique bullet/gun combo, the comparative information is actually very helpful, particularly from investigative and legal standpoints. When he identifies a bullet as having come from a type or types of guns, there are the issues of what can be ruled in and ruled out as a result. If you don't know what the realm of possibilities actually are because your database is missing data, then it can be much harder to make a determination.

 

[sgt127]

@Double Naught Spy

Oh. No doubt. But…I think the odds of EVER recovering a bullet from a Jati at a crime scene is…small.

But, I can appreciate wanting as many comps as possible.

 

[Odd Job]

If you don't know what the realm of possibilities actually are because your database is missing data, then it can be much harder to make a determination.

Exactly!
I found this out the hard way back in 2002 when I was doing GSW research in Johannesburg. In one of my cases a person was shot in the ankle in an incident that involved multiple shooters and multiple victims. I found the X-ray appearances puzzling because of this one projectile component that remained symmetrical even after fracturing the tibia:



The orthopaedic surgeons reduced the fractured tibia with a plate. They had originally wanted to retrieve the projectile but during the operation it was decided that to do so would have rendered the distal tibia unstable and the plating less effective. So unfortunately, the projectile was not retrieved and there was to be no visual inspection of it and the only information we had about the projectile was the radiological appearance on the ankle radiographs. I had CT scans of the limb also, but they added nothing and were degraded by streak artefact (from CT scanning dense metal).

And that was where I was stumped!
So I put out a call for help with the members of the AFTE forum and posted my radiographs there. I got help from those members, especially a member from Hungary and eventually determined what kind of ammunition this was. It was 7.62x25 Tokarev ammunition with a mild steel core. You can read about this case here:

(21) PTLGC: Case 148 (Part 1) | LinkedIn
(21) PTLGC: Case 148 (Part 2) | LinkedIn

Note: you could not narrow down a make and model of firearm in this case because no jacket was retrieved. You would need the cartridge case, or some other kind of evidence beyond what I had.
The point is, before I dealt with this case I had no clue about these kinds of bullets. I had to rely on somebody else's expertise to get the info!

 

[Leon tP]

I watched an old Dragnet episode where the serial number of a specific fire arm was traced back from the bullet marks.

That's pretty amazing...

They had bullet micro-stamping back in the Dragnet days.

 

[bdickens]

Hollywood is fake.

 

[dh1633pm]

Where’s @GunnyUSMC when you need him. I texted him.

 

[LimaCharlie]

Love it when a television detective picks up a bullet at a crime scene and says it is from a 9mm Smith & Wesson.

 

[Riomouse911]

Some guns do have very unique marks left on fired cases or bullets.

Glocks often left a rectangular mark on the primers of fired rounds, because the opening for the firing pin in Glock firearms was rectangular in shape.



Many H&K rifles have fluted chambers. The fired cases look pinstriped from the gas flowing around the case upon firing. (Blown case, but it shows the fluted chamber marks.)



Springfield rifles in .30-06 had unique two-groove rifling that left the two-groove marks on fired bullets, etc.



There are others of course, but these are the most obvious I could think of off the top of my head.

Now there would need to be forensic examination and comparison to determine conclusively if this particular gun fired that particular bullet. As those microscopic markings left on fired cases and bullets are pretty much unique from gun to gun. (We would do what we could to determine who fired what at multiple-officer shooting scenes as an example of why nailing down every recovered bullet fired from every gun fired at the scene would be important.)

Stay safe.

 

[GunnyUSMC]

There’s a lot got goes on in the firearms industry that people don’t know a lot about, not even gun people.
There are guns that have ballistics careerists that are unique, such as Hi Point. Hi Points have an odd number of lands and grove in their barrels and have a left hand twist. Hi Point did this on purpose to make it easier for bullets fired from their guns to be identified.
One thing about the Colt Python is that the barrel has a different twist rate then your average 357 and 38 caliber guns. The Python has a 1 in 14 twist, when you’re other 357s have a 1 in 18 twist rate.
One of the first things that a Firearms Examiner does is determine the caliber of a bullet, and then the rate of twist. They then compare that to a database to get a list of possible guns.
I remember a few years ago, there was a guy that was shooting people that were working in their yards. This was out in a rural area, and the shootings appeared to be random.
The recovered bullets were .358, or thereabout, and 160 gr. The Firearms Examiner, a friend of mine, had forty years experience. He had gone through just about every 357 magnum bullet ever made with no luck. He asked me to have a look, to see what I thought. After having a good look at two of the recovered bullets, I asked Pat if he had thought about rifle bullets. There was the 35 Remington ant the 35 Whalen. These two calibers both used thin jacked bullets like we had.
The caliber and twist rate were compared to the database which matched three rifles in those two calibers. But a third rifle came up, the Remington self loading rifle.
Shortly after gaining this information it was discovered that a report of a missing Remington self loading rifle had be reported at about the time the first homicide was committed.
This gave the detectives the biggest lead in the case. Within a week they made an arrest. The 40 some odd year old son of the man that reported his Remington model 8 missing had taken the gun and was using it to kill people. The guy was a nut case, and claimed that he had hunting tags, like deer tags, for shooting these people.

 

[WestKentucky]

There’s a lot got goes on in the firearms industry that people don’t know a lot about, not even gun people.
There are guns that have ballistics careerists that are unique, such as Hi Point. Hi Points have an odd number of lands and grove in their barrels and have a left hand twist. Hi Point did this on purpose to make it easier for bullets fired from their guns to be identified.
One thing about the Colt Python is that the barrel has a different twist rate then your average 357 and 38 caliber guns. The Python has a 1 in 14 twist, when you’re other 357s have a 1 in 18 twist rate.
One of the first things that a Firearms Examiner does is determine the caliber of a bullet, and then the rate of twist. They then compare that to a database to get a list of possible guns.
I remember a few years ago, there was a guy that was shooting people that were working in their yards. This was out in a rural area, and the shootings appeared to be random.
The recovered bullets were .358, or thereabout, and 160 gr. The Firearms Examiner, a friend of mine, had forty years experience. He had gone through just about every 357 magnum bullet ever made with no luck. He asked me to have a look, to see what I thought. After having a good look at two of the recovered bullets, I asked Pat if he had thought about rifle bullets. There was the 35 Remington ant the 35 Whalen. These two calibers both used thin jacked bullets like we had.
The caliber and twist rate were compared to the database which matched three rifles in those two calibers. But a third rifle came up, the Remington self loading rifle.
Shortly after gaining this information it was discovered that a report of a missing Remington self loading rifle had be reported at about the time the first homicide was committed.
This gave the detectives the biggest lead in the case. Within a week they made an arrest. The 40 some odd year old son of the man that reported his Remington model 8 missing had taken the gun and was using it to kill people. The guy was a nut case, and claimed that he had hunting tags, like deer tags, for shooting these people.

Sometimes you just need a new set of eyes. Sounds like your eyes weren’t burnt out on searching for what wasn’t there so you still had the wherewithal to back up and punt.

 

[film495]

there's probably an app for that

 

[Mike J]

I find myself wondering how the availability of aftermarket barrels for certain makes of semi-auto pistols might play into this. I mean someone could buy an aftermarket G-19 barrel, use it for a shooting, then chop up the aftermarket barrel & dispose of it & put the factory barrel back in. That would be a lot of trouble & require planning but it would seem to get around all this.

 

[Shanvanvocht]

Springfield rifles in .30-06 had unique two-groove rifling that left the two-groove marks on fired bullets, etc.

The two groove barrels were a wartime expedient used on '03A3s and normally only found on original A3s and perhaps some arsenal rebuilds. Springfield and Rock Island '03 and '03A1 production used four groove rifling. My own Raritan Arsenal rebuild has a 1942 Springfield barrel with four grooves.

 

[JohnKSa]

The two groove barrels were a wartime expedient used on '03A3s and normally only found on original A3s and perhaps some arsenal rebuilds. Springfield and Rock Island '03 and '03A1 production used four groove rifling. My own Raritan Arsenal rebuild has a 1942 Springfield barrel with four grooves.

Yup. So if a .30-06 bullet with 2 groove rifling was found, it could be matched, not just to a particular type of gun, but also to a subset of that type of guns.

I find myself wondering how the availability of aftermarket barrels for certain makes of semi-auto pistols might play into this. I mean someone could buy an aftermarket G-19 barrel, use it for a shooting, then chop up the aftermarket barrel & dispose of it & put the factory barrel back in. That would be a lot of trouble & require planning but it would seem to get around all this.

There are certainly ways to get around bullet matching, but just swapping barrels isn't going to check all the boxes in terms of making it impossible to try to trace the crime scene evidence.

Spent cases can sometimes be matched to a gun model based on markings on the cases/primers, and, if the gun is recovered at some point, perhaps to a specific firearm.

It is sometimes possible trace the bullet itself to an ammo manufacturer and perhaps even a specific manufacturing batch and use that to narrow things down.

They also have the same access to aftermarket barrels you do and could try to use that information to determine if an aftermarket barrel was used to fire the bullet. On top of that, it might turn out to be a lot easier to go through a list of people who might be associated with a crime and who bought a particular brand of aftermarket barrel than to determine how many people bought a particular brand of gun. For example, I'd say it's very likely that there have been a lot more Glock 17s sold than Glock 17 aftermarket barrels.

The answer to the OPs question is that it depends. It might be possible to state that a particular bullet came from a particular model of firearm, maybe even narrow it down to a range of manufacturing dates if the rifling characteristics of the firearm used are unusual. Or it might only be possible to say that it came from one of several firearms on a list that all have the rifling characteristics in question.

Rifling characteristics.

Rifling pitch.
Land/groove count.
Land/groove dimensions.
Bore diameter.
Rifling type.