Acids and etching solutions have been used to do this for many years. It takes longer, hence the relevance of this discovery, but it does often work long after the numbers are obliterated visually. My understanding is, similar to this method, it relies on the structural changes made in the underlying metal when the upper layers are stamped. It goes to show you just how tricky materials engineering must be, seeing how the structure of a material can be so easily changed in an invisible way.

So keep grinding even after the serial's no longer visible?

I'd imagine it might be more important to apply the same type of pressure as the stamping process. Assuming there's some maximum compression or structural change that can happen?

Or re-anneal the materials in an oven?

Putting parts of firearms in the oven, does not sound like a safe thing to do if you are planning to fire from them afterwards.

But totally the right thing to do with firearms you're trying to dispose of.

I wonder if peening might be sufficient. http://en.wikipedia.org/wiki/Peening

Sounds certainly impressive, but can't this analysis be stopped/manipulated by simply stamping another serial number or a dot-matrix pattern over the original serial?

And what happens when the area is heated, e.g. with acetylene, short before melting point?

Absolutely some people will adapt with this new knowledge. But I bet that many won't, as they'll have no idea. Not security through obfuscation, but security through people who're trying to cheat being ignorant of the hoops they have to jump through.

It might not help going forward, but I'd wager it'll help close a few cases in the meanwhile.

Honestly I don't understand how utterly stupid criminals can be. Especially guys who planned the crime.

I'd say that being the son of a cop has its advantages in life ;)

I... am not sure what you mean.

For instance, law enforcement in the great state of California is exempt from most restrictions on purchasing handguns, particularly the laws on "unsafe" handguns (which, quelle surprise, encompasses nearly every major manufacturers' latest and most popular models). They are further allowed to give or sell them to whomever they like, including presumably their kids.

$meaning = decode_string("I\'d say that being the son of a cop has its advantages in life \;\)" ;

print $meaning;

"They will never find the bodies."

> "They will never find the bodies."

Heh, if I were on the run for murder the last thing I'd do is post stuff on the interwebs under real name. Especially not these days, when everyone and their dog can track each other (hello, SS#7)...

But I'd say the likelihood of me getting robbed or scammed is lower than the average...

That's what someone one the run for murder would want us to think...

Murder is one of the most stupid crimes to commit - according to Wikipedia, 97.6% of all murder cases are solved.

I don't think heat treatment works... tends to change the hardness of iron-based alloys too much, often a big deal for a firearm (less clear though, whether it's relevant to VINs).

A lot more criminals have access to a $2 file than can get their hands on a stamping machine, or even an acetylene torch. Anything that raises the bar is a net positive.

Perhaps as many criminal have access to a punch or a chisel plus a hammer as have access to a $2 file.

Are all serial numbers stamped?

I would imagine that some might be cut in. Laser? I presume that such numbers wouldn't create the changes needed for this technique.

why not change the metal with say a quick spot weld or smack it with a nail and hammer randomly or small chisel? I wonder if a simple brazing rod would screw this recovery technique