Can you tell?

A tell tail twist rate or rifling anomaly shown on the bullet.
A tell tail extractor/ejector mark?
A dimensional certainty on the firing pin dimensions?
Others?

HK (and clones) roller delayed firearms (MP5s, HK91s, etc.) have fluting in the chambers so you will see evenly-spaced black lines on the brass fired by those firearms.

Sometimes, some small 9mm pistols will tend to drag the firing pin on the primer so you might suspect that brass with such markings were fired in such a firearm. Some early SIG P365s exhibited this.

Aside from that, it’s tough to confidently say that a piece of brass was fired from a certain firearm.

I don't know if the chamber of the Hi-Point is fluted to slow down the extraction, being a blowback pistol.
I can tell that my Grand Power Q100 has a stepped chamber and you can see it on the spent cases. As far as I know also the HK VP9 has a stepped chamber.
Picking up spent 9mm cases at the range you can tell by the primer if they have been shot by a Beretta 92 series. The Px4 probably leaves some signs of rotation on the brass (as well as the typical Beretta bulge on the primer).
Many pistols leave recognizable marks on the spent case: Steyr GB, MAB PA-15, Tanfoglio P25 and many many others. If you are really an expert and you know where to look you can tell many things by only looking close to a brass.

giggitygiggity said:

Sometimes, some small 9mm pistols will tend to drag the firing pin on the primer so you might suspect that brass with such markings were fired in such a firearm. Some early SIG P365s exhibited this.

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Yep, the ejected cases from my little Springfield Hellcat have that firing pin drag marks on the primers.

It's TV. They are not responsible for their actions.

.......if they come from gun responsible sources.

As others have said, there may be some vague tell tale signs pointing to certain models, or even action types.
The fact is though, every machine operation during manufacturing, every file stroke, it all leaves a unique mark and no two are exactly the same.

I believe we have a member who did testing on crime scene guns. @GunnyUSMC

I’ve seen brass out of one particular gun that had distinct swirl marks after firing. The chamber must have been reamed and not touched after that. I’ve never seen another gun cause such ugly marks on the brass. I’ve never picked up brass at the range that was anywhere near that ugly. It would be easily traceable IMO.

gun'sRgood said:

I've seen this in numerous movies where a spent case is picked up and declared that it was fired from a certain gun. I know Glock's have a tell tail FP signature but how many pistols leave marks on a case that can then determine which pistol fired them? It's not only movies.

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No, people that have lived and observed their life around things seem to know a lot of information that others do not.

If you are just watching movies to gain information, you won't be any smarter than they are...see 'Rust' set thread. That said, there are forensic "footprints" firearms leave that are unique. That isn't made up and that can be as true for fired cases as the bullets that go down the barrel, actually more so.

I could recognize cases fired from some of MY guns, simply because the prints on the face of the case or primers were unique.
A gun im not familiar with, or at least ones that don't have a design tell, nope

The fired case that can be identified by some goober (even an informed one) walking up to it, is about as rare as a double-struck penny in a jar of random pocket change.

Such things are 'necessary' to resolve problems in the plot created by a screenwriter, or due to constraints of "run time" for a given show. Thus, you get characters able to be "The Amazing Kreskin" with ordinary objects.

gun'sRgood said:

I really miss Gunny Time!

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He's still 'here' just not as often as before. In his second retirement he has taken to turning wooden bowls, which keeps him occupied out in the shed and not online with "us."

gun'sRgood said:

I know Glock's have a tell tail FP signature but how many pistols leave marks on a case that can then determine which pistol fired them?

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On a forensic level, almost all of them. Think finger prints.

This, may be worth reading.

OP's question about Hi-point 45 case.....the HP 45 (and all of their guns) use a direct blowback system depending on the obscenely heavy mass of the slide to delay the extraction of the case. Not a common operating system in larger calibers except
sub-machineguns where the bolts are the massive element.

In some, the extractor is pulling the case while there is still some expansion of the walls of the case against the chamber and there are scuffs from the chamber imprinted on the sides of the brass. Could also happen with multiple reloaded cases, brass becomes hardened and doesn't rebound after expansion, and Hi-point's chamber are not very highly polished.

In the documentary, he must have been making an educated guess as Hi-points are a lot more common than smg's in real life.

It is a lot easier task to take a suspects gun that you've seized and match it to brass found at a crime scene than to just pick up a piece of brass off the ground and figure out what model gun it was fired from out of thin air.

frogfurr said:

It's TV. They are not responsible for their actions.

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gun'sRgood said:

TV yes, but respectable new documentaries do the same.

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.....just watched a true crime story on the ID channel last night and the LEOs interviewed claimed they determined the one spent casing they found at the scene of the crime to have been fired from a S&W .40 Shield. That is the type of gun they were searching for as the murder weapon. I too questioned the validity, but they didn't.

corpo said:

In the documentary, he must have been making an educated guess as Hi-points are a lot more common than smg's in real life.

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This is known, technically as a "SWAG", or Scientific Wild Ass Guess.

Anyone recall the spent casing, in a little brown envelope, included with new guns for awhile? This was courtesy of the Peoples Republic of Maryland, where they had established a data base of examples of casings, cataloging the twin of the one you found in the envelope. After 15 years, and 5 million dollars, they failed to catch any criminals, and scrapped the program.
As others have said, if there is a recovered shell casing, and a gun that is suspected to have fired it, there's a good chance of a forensic match. But it's tough to do it wholesale.
BTW, I suspect a good cleaning with a bore brush would change the markings left on bullets in the bore, and a similar cleaning would effect the chamber and breechface as well. This last is a SWAG, too.
Moon

someguy2800 said:

It is a lot easier task to take a suspects gun that you've ceased and match it to brass found at a crime scene than to just pick up a piece of brass off the ground and figure out what model gun it was fired from out of thin air.

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Exactly.
If you have a suspect gun, it should be possible to match a fired case to it.
But a random piece of brass, to say it came from a certain model???
Not so much.

halfmoonclip said:

As others have said, if there is a recovered shell casing, and a gun that is suspected to have fired it, there's a good chance of a forensic match.

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Assuming nothing has happed to alter the surface of the breechface/firing pin since the recovery of said casing.

Might find this interesting.

halfmoonclip said:

Anyone recall the spent casing, in a little brown envelope, included with new guns for awhile?

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Yeah, I remember that.

halfmoonclip said:

After 15 years, and 5 million dollars, they failed to catch any criminals, and scrapped the program.

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I didn't know they'd "scrapped" the program. I've bought several new handguns in the last few years, and truthfully, I just never paid much attention as to whether or not they came with a spent casing in a "little brown envelope" in the box. I guess that's just one less piece of brass for me to handload now that they've "scrapped" the program. Oh, well!

halfmoonclip said:

Anyone recall the spent casing, in a little brown envelope, included with new guns for awhile?

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For the longest time I thought those cases went to the bullet that was fired and subsequently sent for entry in the BBB database (Big Book of Bullets). You know, so they could have rifling matches on file.

Wonder how they tell what gun it's fired from if it has extractor marks all over the place? Some of my 9mm brass has been fired in at least 6 different guns.