Can they really match a fired bullet to specific firearm?

Discussion in 'Gunsmithing Forum' started by 76239dave, Jun 27, 2013.

  1. 76239dave

    76239dave New Member

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    On TV shows like CSI they are always matching fired bullets to specific firearms like the rifling is as unique as a fingerprint. I can't see how the rifling marks on a bullet would vary enough from barrel to barrel made on the same machine. Does anybody know if the marks are really that
    unique?
     
  2. indy36

    indy36 New Member

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    Yes, they are. Firing pin punches, extractor marks, they are like fingerprints for guns.
     

  3. robocop10mm

    robocop10mm Lifetime Supporting Member Lifetime Supporter

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    Yup. Ballistic fingerprinting an the NIBN database are very reliable. The one caveat is Glock bullets. The Glock factory barrels do not leave sufficient marks to identify (99% of the time)
     
  4. Buckeyeborn

    Buckeyeborn New Member

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    Hell they can match machine marks on and by a pipe wrench on a pipe bomb part!
     
  5. winds-of-change

    winds-of-change The Balota's Staff Member

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    That is very interesting.
     
  6. deadsp0t

    deadsp0t New Member

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    Agreed.. It's strange because we've all herd the myths about glocks and metal detectors etc but this is definitely a new tidbit for me..
    I'd love to read an article about it.. :intrigued:
     
  7. c3shooter

    c3shooter Administrator Staff Member

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    First is a gross match- caliber, number of lands and grooves, right or left hand twist, then microscopic comparison of marks. Bullets can be so damaged as to not be comparable. Wear for an extended time or deliberate machining/ parts replacement will change the "signature" on the rounds.

    CAN apply to bullets, firing pin/extractor marks, and chamber marks.
     
  8. JonM

    JonM Moderator

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    they also have to get the gun pretty quickly after the crime. a couple hundred more shots or some rust or some vigourous cleaning will changed the characteristics pretty quickly. a 100% match will go to 99-95-90-80-70% in short order.

    its just like matching tire tracks or any other item that wears from use or abuse or time.

    whats more important as evidence will be fingerprints, dna, serial numbers, witnesses, purchase records, interviews, timelines, alibis etc. ballistic evidence sounds cool but its only a very minor player in a court case.

    someone that commits a crime (murder) with a gun is almost certain to have blood spatter or other body fluids on their clothes.

    ballistic matching looks cool on tv but unless you have the murder weapon its not going to go into a CSI computer and spit a name out with X bullet matches Y suspect's gun now go find the gun. thats utter bs.
     
  9. Axxe55

    Axxe55 The Apocalypse Is Coming.....

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    and it usually takes longer than the hour long TV program too!

    ballistics are just part of the entire evidence chain. even DNA is useless until they have a person to compare it to. and just another detail that's used to verify who did what and who didn't.

    good post JonM!
     
  10. deadsp0t

    deadsp0t New Member

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    That makes good sense!! Ty!
     
  11. DrumJunkie

    DrumJunkie New Member

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    I have a friend that is a tool and die man that has been going on about this for a year or so. His thought is with tool steel being much better than it was years ago it can be more likely now days to make more than one bbl that can have similar enough marks that it could be argued that they have the wrong gun.
    I don't see it. I admit I'm no tool maker but still....there are so many other variables to consider other than the bbl and chamber of a handgun. Firing pins/strikers, extractors etc make it a lot harder to deny the bad gun even if you could make more than one bbl with ther same lans & grooves. Plus the little things we all do with our guns. The manner of cleaning, frequency of cleaning, type of ammo used over time. All these things make a gun a lot more individual.

    I guess if one was to use a disposable bbl and keep your matching number bbl for if someone asks to see your gun. :confused:

    There was some book or magazine I remember years ago that this German guy had figured out a way to wrap rounds in a manner that kept the bullet from touching the bbl. It's been years and I can't remember the specifics anymore. It seems though that was with a rifle not a handgun. But I honestly can't remember anymore. It's an interesting concept though Basically the paper wrapped round would use the paper to grab the rifling and spin the round and fly off after the round left the bbl at some point. It seemed an awful lot of work and I can't believe it was very accurate but it was supposed to work as an untraceable round.
     
  12. c3shooter

    c3shooter Administrator Staff Member

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    Junkie- guess you have never seen these, huh?

    accelerator.jpg

    That is the Remington Accelerator. Made in 30-06, .308, and 30-30. The projectile is a 55 grain .25 caliber bullet, sitting in a plastic sabot. The sabot leaves the bullet about 18 inches from the muzzle. The .308 had a claimed velocity of 4,200 fps, the 30-06 about 4,500.

    Rifling never touches the bullet, only the sabot.
     
  13. Axxe55

    Axxe55 The Apocalypse Is Coming.....

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    i have seen them before, and have several times thought about buying some, but are they accurate?
     
  14. clr8ter

    clr8ter New Member

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    And what is the purpose? They are faster than the normal bullet for that caliber? If so, to what end?
     
  15. 76239dave

    76239dave New Member

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    The tool and die guys argument was my thought when I first posed the question. Extractor and firing pin marks are only relevant if you have the brass. Maybe there are still microscopic differences between barrels that came off the same machine one right after the other but I'm not convinced they would show up on a bullet.

    Anyhow, thanks to everyone who posted. Good food for thought.
     
  16. DrumJunkie

    DrumJunkie New Member

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    Well..Like I said I"m no tool maker. My frfiend is very good at what he does s I really have no way to doubt him. The idea that the same tool will make more barrels today then they did even 30 years ago does make it a valid question. Being I don't see many peopel in a shooting hunt down their brass though I think that is sometime to think about. Brass is much softer than the steel in the gun. So it's not far fetched to think that there can be a unique transfer of tool marks etc.When yo uare looking at slugs and cases under high magnification I would imagine those little marks will show up just fine..

    I've seen and read about the ammo before but I've not handled or used it. So I have no working knowledge of how well it works.I had forgot about those truthfully. I got on the paper wrap guy and went and let my CRS syndrome take control again.:eek:
     
  17. c3shooter

    c3shooter Administrator Staff Member

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    Paper patched bullets were very common for big bores rifles around 1890-1910 era.

    Re: Accelerators- accuracy was about as good as the parent caliber/rifle. Use? Faster than crap varmint round. Standard 30-06 is about 2,600 fps. These were 4,500 fps. For some years, they laid claim to being THE fastest factory rifle load in the world. May still be. My .220 Swift runs about 4,100 with really hot loads. Even the .204 Ruger is not THAT fast.

    You CAN buy the sabots and reload your own- which makes some very interesting 7.62x39, and 7.62x25 ammo.....

    BTW- when a forensic investigator is comparing bullets, this is what he sees. The microscope has 2 sets of lenses, lets him put one bullet under each, and see if they match when being rotated. Red line is the end of one bullet, start of another. HIGHLY magnified.

    ballistic comparison.jpg
     
    Last edited: Jun 30, 2013
  18. hmh

    hmh New Member

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    Popular Science or Popular Mechanics did a test were they sent test bullets and arms to the best crime labs in the country and they almost all came back with different results?
     
  19. c3shooter

    c3shooter Administrator Staff Member

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    Got a link to the story?
     
  20. hmh

    hmh New Member

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    I read it the good old fashon way