Technical Question for the CSI Guys

[AJGUNNER]

So I was watching an investigation show on TV last night about a murder and how it was solved with tying the gun, brass, and bullet all together. The bullet was a pass through and was damaged beyond use for matching it to the barrel. The gun was recovered along with a single piece of 9mm brass. In the end they were able to match the gun to the fired brass based on the impression of the chamber on the brass and also the extractor markings.

So my question is this: If the brass has been reloaded multiple times, then fired out of multiple different pistols, would they still be able to tie it to the pistol that fired it the last time???

This was one of the re-enacted crime shows, not one of the CSI drama shows.

 

[GunnyGene]

Might take some work with a high powered microscope, but probably yes. Any markings from previous pistols would be overlayed by the most recent.

 

[SAJohn]

He should have used a Ruger revolver with 9mm frangible ammo and tossed another persons 9mm brass on the ground.

 

[Pat-inCO]

This was one of the re-enacted crime shows, not one of the CSI drama shows.

Was that John dingle-dumb's (Walsh) "Justice Network" by chance?
The things on there are coming to be pure "stuff". The AST segments
are good, but most of the rest is too far out for even liberals to swallow.

I would love to find out where he is getting the money to push that "stuff".
:roll: I would like to get a grant to study in-grown toenails. :roll:

 

[AJGUNNER]

This was one of the re-enacted crime shows, not one of the CSI drama shows.

Was that John dingle-dumb's (Walsh) "Justice Network" by chance?
The things on there are coming to be pure "stuff". The AST segments
are good, but most of the rest is too far out for even liberals to swallow.

I would love to find out where he is getting the money to push that "stuff".
:roll: I would like to get a grant to study in-grown toenails. :roll:

Yes it was on the Justice network. I have this addiction to Alaska State Troopers. Been there a few times and know a couple of the troopers. Just enjoy the scenery, lifestyle, and watching all the drug and alcohol related law breaking idiots.

 

[Bear Paw Jack]

I would assume the bullet was at the crime scene, along with the brass, and I assume the gun was close, they had to begin with the assumption that they all came from the same gun, just so some idiot defense attorney said, "how do they know the bullet came from that gun?" So in answer to your question yes they can determine all that. However, there has never been a case where they started with a piece of brass and were able to narrow it down to what gun, or even what kind of gun it came from. That's the reason that they no longer are requiring brass to be submitted to the state, irregardless of the original theory that it needed to be at tremendous expense to all kinds of people including gun manufacturers, the state, etc. I see where Maryland has decided it's no longer required, apparently they are slower on the uptake than some folks are. Even California (I believe) has quit requiring it, since it proved nothing.

 

[powder smoke]

So my question is this: If the brass has been reloaded multiple times, then fired out of multiple different pistols, would they still be able to tie it to the pistol that fired it the last time???

Most reloaders tumble brass to clean them the media is abrasive clean and polishes.
Then resized I would imagine most marks from a chamber would be all but gone. Stuff
looks new at that stage. So I would say absolutely. I'm no expert just my opinion. ps

 

[Rick Courtright]

So my question is this: If the brass has been reloaded multiple times, then fired out of multiple different pistols, would they still be able to tie it to the pistol that fired it the last time???

Hi,

On TV? You bet!

In real life, see the thread about the State of MD dropping its fired case requirement because it seems not a single crime's been solved with one in something like 15 years. So with CSIs who do their field work in blue coveralls and boots instead of revealing designer outfits and heels, I have my doubts about your scenario playing out. Anything's possible, of course, like maybe the reloader had tumbled the brass well enough to eliminate ALL previous markings so only those from the last firing are visible, or Gunny's microscope can somehow "layer" any remaining prior marks. But probable?

As an example, just thinking of my own brass, fired from the Bisley: I just wash my brass, don't tumble it. The chambers say "Ruger QC" all over them in that they're not burnished, very rough, and I'm sure each chamber's drilled with a separate cutter, so there's a distinctive set of tool marks in each one which leaves radial marks in the brass. Then my resizer, even though it's carbide, may leave some axial ones of its own, or at least disrupts the chamber marks. Now, I start with a brand new round, fire, reload, and repeat using a different cylinder each time until it's been thru all six chambers. Deciphering the scratch pattern's gonna be a real job of pickup sticks by then!

So... I'm just not too sure.

Rick C

 

[Don Lovel]

Experienced microscopist here, yes abraided by rough chamber, slightly deformed, etc. You can see overlays of chamber marks on a fired case, as well as firing pin indent location, depth, width, pointed, flat tipped, round tipped, a extractor or ejector mark and at some levels identifying the fired powder type by residue on the bullet, fired case, or gun or perp's hand chemistry match.

 

[JFB]

 

[Precision32]

Just use a revolver and you don't have to worry about your brass. :mrgreen:

 

[Mobuck]

I could never make it on CSI. Those people find brass in the grass, weeds, leaf clutter, gravel piles, and all sorts of places. I can watch it hit the ground (not bare ground but short grass/gravel)and lose it. I'd call BS on a lot of the things the TV show purports as fact.

 

[Fox Mike]

What is even more amazing is they can tell it came from a Colt .38 special just by looking at the mangled half a bullet. :shock: There would be no reason to believe that it could have come from a .380, a 9mm, or a 357.

 

[Charon]

I think one basic assumption is that criminals seldom reload ammunition. Thus, you will usually have once-fired brass to work with. Few criminals are going to stick around the crime scene long enough to recover their brass. A revolver would be a different story. I believe some gun makers use different numbers of lands and grooves, as well as (sometimes) different twist rates including right-hand or left-hand twist. Some auto pistols use polygonal rifling. Those factors would not make it possible to identify a particular gun, but would make it possible to exclude whole bunches of guns.

 

[toysoldier]

If the "expert witness" had to admit on the witness stand that the casing had been fired in more than one gun, it would give a good defense attorney some wiggle room.

 

[blume357]

One of my favorite shows.. NCIS is always checking 'the gun' against some registry....

It's TV, they make it all up... you realize this when they throw some wild thing in that you know something about... but just accept all the stuff you don't.

No different than the media and news... trust me, it's true.

 

[Jeepnik]

One of the reasons some states wanted a fired case sent to them was to check them against cases recovered at a crime scene.

One state is doing away with the practice. About 15 years of doing it and not one case solved. Besides, what idiot would leave brass at a murder scene. Gesh, don't the fools watch TV. :mrgreen:

As an aside, I wonder how many people have used knowledge gained from CSI to avoid being caught. Got to be a few.

 

[k22fan]

To enjoy the various CSI type shows I've watched you have to treat them like the super hero shows that came before them. Without even examining their details they are too unrealistic to take seriously.

Getting back to the original question, no one has mentioned microscopic examination of the breach face imprint on the primer. 9 mm pressures are the same as .357 and .44 mag. That is enough pressure to impress the breach face's tool marks into the primer. That would match a reloaded case to the gun.

 

[mohavesam]

Any self-respecting murderer uses a revolver or HP rifle and takes their brass with them. Only an amateur uses an automatic, which spits evidence all over the hacienda.
I thought everyone knew that since Joe Mannix explained it to me decades ago?

Any TV badguy who leaves a shell casing at the scene, then KEEPS THE GUN AROUND, deserves the chair!

 

[JFB]

Yesterday, I saw a Joe Kenda, Homicide Hunter episode where they only had the round from the body and identified they were fired from a 1868 Colt Army!

 

[Jimbo357mag]

Most criminals use stolen guns that are untraceable and they don't care about their brass. ...and they get caught on a regular basis.

Those CSI guys are good and fast also.

 

[Jeepnik]

Any self-respecting murderer uses a revolver or HP rifle and takes their brass with them. Only an amateur uses an automatic, which spits evidence all over the hacienda.
I thought everyone knew that since Joe Mannix explained it to me decades ago?

Any TV badguy who leaves a shell casing at the scene, then KEEPS THE GUN AROUND, deserves the chair!

Thought his small of the back holster was cool til I grew up and realized what falling on it would do to your spine. Still, he had style.