Crystal Pattern Matching Recovers Obliterated Serial Numbers From Metal

chicksdaddy writes Criminals beware: researchers at the National Institute of Standards and Technology (NIST) have figured out how to recover serial numbers obliterated from metal surfaces such as firearms and automobiles — a common problem in forensic examinations. According to this report, NIST researchers used a technique called electron backscatter diffraction (EBSD) to read, in the crystal structure pattern, imprints on steel that had been removed by polishing. ... The more perfect the crystal structure, the stronger and clearer the pattern. Software can then calculate the pattern quality to reveal crystal damage; areas with more damage produce lower quality patterns. In the NIST experiments, described in Forensic Science International, researchers hammered the letter 'X' into a polished stainless steel plate. The letter stamps were as deep as 140 micrometers, meeting federal regulations for firearm serial numbers. The researchers then polished the metal again to remove all visible traces of the letters, and collected the EBSD diffraction patterns and pattern quality data and analyzed them for evidence of the imprints.

Comments

Overstamp First?

[theshowmecanuck]

What if you use some tool and hammer to overstamp the serial numbers. Like scribbling over it. Then grind it down. Or if it is in a place that can be heated and cooled... like annealing... where any loss in strength from the operation, were it to happen, wouldn't be an issue. Would that change the underlying crystal structure significantly. I'm sure it would affect it some, but would it be enough to allow the crystal structure to 'reset' and erase the original stamp marks?

Re:Overstamp First?

[Kardos]

You'd want to match the force used on the original stamp, else your 'decoy' numbers and letters will leave crystal deformation pattern that differs in intensity from the real digits. Probably easy if you're the manufacturer, but a touch harder if you're some guy with a hammer.

3D print the gun,

[invictusvoyd]

And this becomes largely irrelevant

Re:3D print the gun,

[Anonymous Coward]

Why 3d print? Easier to just go to the hardware store and get some plumbing parts. Also won't explode in your hands after a few shots.

Re:3D print the gun,

[ls671]

There is a legislation coming up forcing all 3d printers to incorporate a serial number in all 3d printed guns.

Re:3D print the gun,

[Anonymous Coward]

Removing markings from metal is an easy process that can be done with hand tools and power tools. If you were to remove all of the metal behind the markings i would expect the analysis to fail.
A polymer gun is easier, as you only have to grind off the metal plate holding the markings and are still left with an intact tool.
Creating a working gun, or the part of the gun that requires a serial number is not easy. You can try to use a 3D printer, a CnC Mill or in come cases, like the AK-47, a shovel and hammer. It is not easy.
You now have to procure the rest of the weapon and assemble it. Purchasing lots of parts that should fit, usually do not. If someone has the time, intelligence, resources and skills required to make a gun, they can use those four things to build far worse things. Someone shooting up a mall is going to yield fewer casualties than someone blowing up a large portion of it or releasing poisonous gas into an enclosed space.
Crying wolf with 3D printing did wonders for ratings but it's not putting guns into the hands of criminals. A pipe and a nail, steel and a welder, the black market, are all much easier methods to procure a gun. A quick look at prisoners and oppressed cultures shows how easy it can be to make a weapon. 3D printing isn't one of them.

If you happen to have access to something awesome like a metal or commercial plastics (much stronger than PLA and ABS) 3D printer, please use it. If you do make a gun and are worried, you can always add your own markings and register it.

Re: 3D print the gun,

[O('_')O_Bush]

Yea, you can literally buy a piece of plastic that just requires a Dremel to roughly hollow out, and from there build a complete AR-15 in less than an hour. No serial number, little to no knowhow, just a hammer, pin punches, a Dremel, and about $600. 3D printed guns are nothing more than moral panic bullshit. But so is gun-grabbing. Statistically speaking, there are few rational reasons to ban firearms, but this discussion is popular amongst people who have gun phobias. You are 50x more likely to be sent to the hospital due to a dog attack than to be killed by a firearm. I know those two things are in no way equivalent, but I have never heard someone suggest banning dogs, despite the greater frequency of harm. The reason why the largest demographic (by a large margin) for the victims of the 11,000 or so gun deaths unrelated to suicide each year are young black men, and the highest proportion of those deaths (also by a large margin) are from handguns, is largely due to the reason why that same demographic is the highest (by a large margin) in prison. The drug economy. But no, let's discuss banning "scary" looking guns like AKs and ARs, despite these being the most popular rifles in the U.S. while simultaneously their use in homicide and crime is almost unheard of (except for the black swan mass (10-30) shootings that happen with them once every decade or so).

Is this new?

[tsotha]

The FBI has been recovering filed off serial numbers for at least a decade based on the changes in metal grain that result from stamping. Is this just a more sensitive method for doing that?

Re:Is this new?

[sound vision]

It looks like this is a more advanced method to accomplish the same thing. Meaning that recovering sanded serial numbers is not new, but this particular way of doing it is.

Re:Is this new?

[felrom]

The problem is that most people have watched too much CSI and think that a serial number on a gun is equivalent to a magical beacon that instantly homes in on the person who committed the crime. Just look at all the hysteria in the last few years over 3d printed guns and 80% firearms: it all revolves around the line of reasoning of, "if a criminal used this in a crime, we couldn't trace it back to them." The whole breathless panic never stops long enough to understand that criminals aren't going out and buying new guns from licensed dealers and having their names linked with serial numbers in the first place.

Re:Is this new?

[robbyb20]

I'd be interested to see the life of a gun. From first initial theft(or undocumented sale) to how many hands one firearm passes thru. It would be interesting to see how much separator there is from the original documented owner.

Re: Is this new?

[BlueTrin]

The problem is that if you base yourself on declared data you will have a massive bias as criminals are unlikely to provide information. Therefore your data will be about legally owned guns which is not the data you would need for crimes. I still agree with you that it would be interesting.

Overstamp twice.

[Okian Warrior]

If you do it stupidly, like put a "1" through an "A", it would be fairly obvious and narrow the search down.

Punching 1 through an A leaves the firearm with two possible choices in that digit. Do this for 9 digits, and you get 2^9 = 512 possibilities. Punch twice through each digit and you get 3^9 possibilities.

In fact, punch *all* the digits in each position, then file it down.

This will rapidly be entered into the "big book of best practices" for criminals.

And it's also a moot point, since easy access to guns reduces crime, and it's likely that 3-d printed guns will be easily available in the next decade or so.

(And so what if the 3-d printed gun is reliable for only the first couple or shots? That only means that you use your 3-d printed gun that took 2 hours to print and $3 to build a couple of times and then melt it down.)

Re: Overstamp twice.

[ihtoit]

Pot, meet kettle.

You can't pick and choose between which states have tougher gun laws either for the simple reason that CRIMINALS DON'T GIVE A FUCK FOR THE LAW!

Gun crime statistics follow the trends as to 1. places where it is EASIER to get your hands on a weapon and 2. how easily you can move said weapons across borders. Absent water barriers such as THE ENGLISH CHANNEL which makes it more difficult to move weapons across land borders, gun ownership in England is clearly lower than in the rest of Europe whether or not and immaterial as to whether or not it is LEGAL to own a firearm. In Europe you can take a gun from your starting point in Syria and NEVER GET YOUR FEET WET ALL THE WAY TO PORTUGAL and shoot up a hotel lobby.

Re:Overstamp twice.

[Dutch Gun]

No need for such over-complicated and over-engineered solutions.

Each gun already imprints a unique microscopic signature on a bullet and casing. Just submit a scan of a fired bullet and cartridge to a central database for each new firearm sold, where it's linked to the serial number. They're test-fired before use anyhow, so I'll bet the manufacturer could easily add a forensic-type scanner to the manufacturing process, likely completely automated as well. Then we wouldn't have to rely on serial numbers on the gun at all then. Any bullet in good condition could likely be linked with the serial number using that database.

Law enforcement already uses this technique, but can only perform matching tests if the gun or additional fired rounds are found. This wouldn't require any new technology at all, only new procedures.

Millions of dollars in research.

[He Who Has No Name]

Defeated by a $59 Dremel tool that completely removes the metal from that area of the frame...

Etching does the same thing

[hankwang]

It has been possible for decades to recover serial numbers by chemical etching, which is sensitive to changes in the crystal structure. All you need is a polishing implement and a bottle of etching gel. What is the added value of this EBSD technique? I can see a big disadvantage: you need equipment (a scanning electron microscope) worth a few hundred kEUR and the object with the erased serial number needs to fit into the vacuum chamber of said equipment.

The article mentions that etching techniques don't always work, but they don't state that their technique does work on samples for which the etching method doesn't work...

Ok, what about recrystalization?

[wierd_w]

Metal grain boundries change if you heat the metal up. This also removes the temper, but rapid heating followed by rapid cooling (Such as by very high speed friction sanding, then submersion in water or oil) will change the crystal grain structure of the metal pretty deeply if done right.

Failing that, sanding off the top layer, then applying heat with a heat gun for a few minutes, then clenching with a cold oil pour will have the same effect, but more reliably.

Seriously, this is how heat treatment of steels works. Steels and other metal alloys go through various phases of crystal growth types under different temperature and pressure environments. They grow when hot (but not molten) which is why the metal weakens. If you heat it up hot enough, this processes changes into annealing where the crystals break down from thermal forces and the metal becomes amorphous. Flash cooling results in a densely packed matrix of tiny metal grains, which strengthens the metal.

Seriously-- all you have to do is alter the crystal growth pattern under where the serial number was. Heat treatment will do exactly that.

Re: Heating the metal to erase

[Qzukk]

Maybe not in Europe, but here in the US reloading casings is a thing. http://www.wikihow.com/Reload-... You do need to buy the right equipment though and these days it probably does get you put on lists on either side of the pond.

Casting bullets isn't the preferred way to make them (since these days people want jacketed bullets hollow points etc) but melting lead and casting them from molds is trivial.

Could Be Handy in the Gun Shop

[CanHasDIY]

This could actually be useful for gun shops, since we have to meticulously catalog the serial numbers of all firearms that come in and go out. We often get older (like, 150 year older), used firearms where the serials are worn down and difficult to read, even with a jewelers loupe.

Or rather it would be useful for gun shops, if the process isn't as cost-prohibitive as I presume it will be.

Re:Could Be Handy in the Gun Shop

[ihtoit]

yeah, it's a requirement in England now and retroactive to firearms made after 1968. That said I have a Webley Junior Mk.II from 1949 with a serial on it (pretty much all Webleys have serial numbers, they've been going since 1925 - my two Stingrays also have serials).

Re: Heating the metal to erase

[ihtoit]

I make my own slugs. It's easy. I don't load casings though. I use air rifles. Don't need gunpowder. Just need lead. As for jacketing, laminate electrodepositing is a thing I've been doing for a decade. Fifty or so layers of copper on a slug and it's pretty damn hard (and plated up to maybe a fiftieth of an inch). It's also a handy way to bring a .20 cast up to match barrel tolerance.

Anecdotal, admittedly, but....

[codeButcher]

... how to recover serial numbers obliterated from metal surfaces such as firearms and automobiles ... In the NIST experiments... researchers hammered the letter 'X' into a polished stainless steel plate.

Just had a look at the few automobiles and firearms I own. None are made out of polished stainless steel plate.

Also, while my oldtimers are stamped, I recall seeing a few items of more recent manufacture that had the s/n milled into the substrate.