.22 Caliber Rimfire Forensics?


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Racer997
August 20, 2009, 11:50 AM
A friend and I were discussing forensics and .22 caliber rimfire. I have heard over the years that .22 caliber rimfire, mostly because the bullets are soft lead and are more prone to deformation and disentergration, aren't as easily matched to barrels forensically as opposed to copper clad bullets which are far more apt to leave marks that can be matched to a barrel more conclusively. Is there truth to this? What about chamber/extractor/ejector markings on spent .22 caliber rimfire brass?

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DoubleTapDrew
August 20, 2009, 04:18 PM
From what I've gathered reading this forum and others, a crime has never been solved/linked/convicted by "ballistic fingerprinting" outside of TV programs like CSI.

rcmodel
August 20, 2009, 04:27 PM
I don't believe that to be true at all.

All major Law Enforcement organizations have ballistics labs, and can match bullets to crime weapons easily.

If no crime has ever been solved with it, they wouldn't waste all that money doing it.

I can recall one murder case right here in my city recently that was solved by matching bullets recovered from a body dumped miles away, with a gun recovered from the crime scene and traced back to the shooters girlfriend.

Without the ballistics match, all they had was a .38 revolver over here and some bullets in a body over there.

As to the OP's question.
Yes, lead bullets can be matched to a gun unless terribly deformed.
As can the cases that came from the gun.

Every firearm leaves distenctive microscopic marks from the chamber, bolt face, extractor, and ejector that are not going to exactly match any other gun.

rc

akodo
August 20, 2009, 04:51 PM
All major Law Enforcement organizations have ballistics labs, and can match bullets to crime weapons easily.

If no crime has ever been solved with it, they wouldn't waste all that money doing it.

I think the truth is midway between these two.

For starters, yes, there have been millions spent on big databases of rounds and cases collected after shooting BEFORE the gun has been sold. It is true that these databases have not been used to solve any crime. It appears that while ballistics is good enough to say 'we have 1 bullet from the crime, and 1 bullet fired in the lab, they look VERY VERY similar' while it is another to say 'we have 1 bullet from the crime, and 10000 bullets in the database, and ONLY ONE looks very very similar'

However, when a bullet is recovered and a gun is recovered, you can get a pretty solid link...if the bullet holds together well.

Obviously, bullet that fragments extensively will be nearly impossible to match. A FMJ that holds together very well will be easier, same with modern JHPs as the base normally holds together to improve penetration. I am not suprised to hear that 22LR bullets don't hold together very well and hence are more difficult to match

Big_E
August 21, 2009, 12:31 AM
My dad specializes in this sort of stuff for a career. However, he is out of town right now so cannot reply in a timely manner.

IIRC, he said that they don't really bother matching .22 bullets because they are so difficult to read and if they do recover the round from a victim that it is usually so deformed it would be impossible (mostly lead but sometimes copper jacket too.)

And yes, cases have been solved by linking bullets to guns.

lebowski
August 21, 2009, 12:46 AM
From what I've gathered reading this forum and others, a crime has never been solved/linked/convicted by "ballistic fingerprinting" outside of TV programs like CSI.
I think what you mean is, they don't solve crimes by running the ballistics through a database and finding a match. NYC is the only place in the US with such a database as far as I know, and their program has solved zero crimes despite millions invested.

However, if they have a suspect, you'd better believe many a crime has been solved (or they helped get a conviction) by matching up the bullets.

tkopp
August 21, 2009, 12:47 AM
I imagine barrels change due to wear, cleaning, and what sort of rounds one has fired recently. A test fire before the barrel shipped would be a lot less useful than a test fire 'recently' after a bullet was recovered.

Big_E
August 21, 2009, 01:08 AM
Hmm, I can't find the Forensic Files episode i am looking for.

Polygonal rifling is much harder to match because the rifling isn't as deep. Barrel wear does happen but most weapons used in crimes are not in the hands of competition shooter's that fire hundreds of rounds through them each month. Therefore, throughout a firearms life in the hands of a criminal the rifling does not change enough to obscure the unique rifling. Unless a criminal runs a screwdriver or tool in the barrel to mess up the rifling (and most of the time they only get the front portion of the barrel and not the entire rifling, covered in the FF episode I am looking for.)

I did bullet matching for an 8th grade science project, blood spatter for 7th. So from that, the Forensic files episodes i have seen, and conferences I have attended I make my claim. My old man would know a whole lot more than me though.

cchris
August 21, 2009, 02:49 AM
From what I've gathered reading this forum and others, a crime has never been solved/linked/convicted by "ballistic fingerprinting" outside of TV programs like CSI.

I don't believe that to be true at all.

All major Law Enforcement organizations have ballistics labs, and can match bullets to crime weapons easily.

If no crime has ever been solved with it, they wouldn't waste all that money doing it.

In the less wealthy areas, you usually don't see many crimes solved by ballistics labs. In SC this would make it even harder, given that transferring ownership to another person requires no paperwork at all, and a murder weapon would have to be found in order to incriminate the original owner of the gun (never mind that he might've sold it 10 years ago).

From what I've gathered (from the cases I have actually seen), few cases in this state get solved "CSI style". Unless it's a politician, law enforcement officer, or someone else of high standing, spending thousands of dollars to determine who killed a homeless man isn't really worth their trouble.

Oyeboten
August 21, 2009, 05:25 AM
Unless a Forensic Lab has the Gun the Bullet(s) had been very recently fired from, with few to no intervening shots, TO establish a 'match', they are really quite helpless to say what Arm the Bullet(s) were fired from.

They can conjecture in broad generalizations, based on presumed or deduced Calibre, and present weight or other characteristics of recovered Bullets, and, that's it.

They can in effect, describe a recovered Bullet...as such...and in the condition it is in...and this in itself may not be enough to determine specific Calibre actually, anyway.

Only rarely, can a Forensics Lab say what make-model Bullet it is/was...let alone, to say what Arm it was fired from.

Carl N. Brown
August 21, 2009, 01:46 PM
"Ballistic fingerprinting" as in bullets or casings taken at the factory have proven useless in connecting crime scene evidence to a perp. Comparing crime scene evidence to weapon found in possession of a perp is the only way it has worked in real life.

lanternlad1
August 21, 2009, 10:35 PM
http://www.snipershide.com/forum/ubbthreads.php?ubb=showflat&Number=504301&fpart=1

toivo
August 21, 2009, 11:02 PM
I think what you mean is, they don't solve crimes by running the ballistics through a database and finding a match. NYC is the only place in the US with such a database as far as I know, and their program has solved zero crimes despite millions invested.

Actually, all of New York State has it, and so does Maryland. But you're right that it hasn't solved any crimes. NYS registers all pistols. The idea that anyone would commit a crime with a gun registered to him/her and then leave casings at the scene is ludicrous. Crimes are committed with black-market and stolen guns. To solve anything, the cops have to find the gun and connect it to the perp. The database is worthless.

Racer997
August 21, 2009, 11:08 PM
"So we aren't allowed to even think about the situation at all? Then when we don't have an answer, ask those that might know?"

Thank you. No man ever got smarter without asking questions, right? Indeed I don't know so I ask.

However, since a few asked why I'm asking, let me enlighten them: this question was born from a discussion I had with a friend regarding John Ross's "Unintended Consequences". A great read...who here has read it? There's a part in the book where some characters do some close-range sniping with .22 rimfire. My friend and I were discussing that, and, well, here we are asking more and broader questions.

Thanks for the input, guys.

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