Real-world criminal science questions.

[Rupert]

Originally Posted by (E)

The rifling marks made on the bullet may change after a number of additional rounds have been fired down the barrel. Though the differences may be just legally different rather than fundamentally different.

Use abrasive paste and a steel bore brush before and after. While the rifling will still be apparent on the bullet, and thus the make of gun might be distinguishable, the scratches on the bullet will be rather different from the ones the barrel will leave on test bullets after such treatment.

Also, note that bullet to gun matching is not an exact science, and in some cases is more wishful thinking than anything else. Use common mass-market over-the-counter ammo in a common firearm, do what I say above (and possibly give the firing pin and extractor a good scrub as well), and this sort of forensics will be quite hard, which is not to say that if you character is already a suspect the evidence won't be used anyway, because being able to say "this guy's gun could have been the one is still useful.

[Black Leviathan]

Originally Posted by Anaraxes

The murder rate in Mexico is about 2-3x that of the US, with the murder-by-firearm rate being slightly higher (1-1.5x). Wikipedia tells me that the number of police in Mexico is about the same as the US (366 per 100,000 population, versus 391 per 100,000 in the US).

What extra resources did you have in mind?

As I'm told, because of their level of firearms regulation, gun crime is Mexico has a heavy overlap with organized crime. They have specialized investigation forces for gun crimes. The police are more invasive than they might be for other offenses when it comes to those crimes, commandeering civilian security footage. Areas with high gun violence will have stop-and-frisk patrols. People with guns registered matching a type used in a crime are questioned or even taken into custody. It's not that they have different tools for law enforcement but they have different limits on their ability to impose law over civil rights and gun crime happens less often so the public reacts more strongly to it.

[Varyon]

As has been alluded to, some consideration should be made for the likely circumstances in which the characters will be leaving bodies behind - and the identities of those bodies. If the police are going to dig into the case, a bunch of bodies from various walks of life, most of whom appear to have been actively involved in a gunfight with an unknown party at the time of death, are going to raise a lot of red flags, and their recent history is certainly going to be explored. Their surviving accomplices may be detained and questioned prior to the PCs being anywhere on the radar, and the police may well spend significant resources trying to track down their patron without realizing Nostradamus D Feratu was actually that strange pile of ash the techs were never able to make sense of. I suspect organized crime and/or cult activity will be strongly suspected, so as long as the PCs can stay off those radars, they may be safe.

Still want to make certain they don’t leave matching clues at crime scenes in two different cities, of course, as such a link will go a long way toward pointing the authorities in their direction.

[Johnny1A.2]

Originally Posted by Black Leviathan

Ballistic pattern is pretty tough to stick as evidence because it's not as conclusive as the police want you to believe. A decent lawyer can either make it inadmissible or question it to the point of making it dubious to the jury.

Which touches on a tangential but very important issue: do the hunters have a good lawyer on standby? If they don't, they should. It's just as much a basic part of the equipment for a modern-setting team of monster hunters as firearms and body armor. If they can't afford it...they might not should be hunting monsters, just as if they can't afford the weapons.

Sooner or later, they're gonna need that lawyer.

[Johnny1A.2]

Originally Posted by Varyon

As has been alluded to, some consideration should be made for the likely circumstances in which the characters will be leaving bodies behind - and the identities of those bodies. If the police are going to dig into the case, a bunch of bodies from various walks of life, most of whom appear to have been actively involved in a gunfight with an unknown party at the time of death, are going to raise a lot of red flags, and their recent history is certainly going to be explored.

So remember, kids, make sure your permits and other paperwork are in order. If a potential team recruit has a criminal record...think carefully. Is what he brings to the team worth the liability of that record?

As someone once said of a Call of Cthulhu game...packing heat? Pack a permit!

Make sure you know the basic local laws about weapons possession, open carry and concealed carry, etc. You don't want to successfully put down the vampire and save the kids and then end up in prison for some legal violation you could have avoided.

If humanly possible, do not engage in violence with the cops!! Underline that. Embolden it and carve it. If the monster is a cop, then you've got a Very Special Case Situation on your hands, treat it that way. It's bad enough fighting monsters, you don't want the police after you too if you can help it.

A good, modern-day monster hunters game that pretends to even semi-realism is going to involve a lot of planning and scouting out, as well as shooting the monster.

[Polydamas]

Originally Posted by Black Leviathan

As I'm told, because of their level of firearms regulation, gun crime is Mexico has a heavy overlap with organized crime. They have specialized investigation forces for gun crimes. The police are more invasive than they might be for other offenses when it comes to those crimes, commandeering civilian security footage. Areas with high gun violence will have stop-and-frisk patrols. People with guns registered matching a type used in a crime are questioned or even taken into custody. It's not that they have different tools for law enforcement but they have different limits on their ability to impose law over civil rights and gun crime happens less often so the public reacts more strongly to it.

Yes, the same in most countries: shootings which are not domestic or hunting accidents are usually related to organized crime. And in the past 15 years large parts of Mexico have been in an insurgency with the paramilitary law enforcement which that implies ... Wikipedia gives an intentional homicide rate of 25 per 100,000/year, compared to 0.7 to 2.0 in most developed countries and 5 in the United States, wherever they got those numbers I suspect they come from a time when the cartels were fighting each other and the government. If tens of people were found murdered in Canada or the New Country that would be front-page news until the culprits were found, during the drug wars in Mexico or the civil wars in Iraq that was a monthly occurrance.

If monster hunters are going to be illegally shooting people and Things with the Shape of a Human, they will be much more likely to get away with it somewhere in the middle of civil strife, or if they keep their violence to the margins of society (which might include a tight-knit immigrant community which does not cooperate with police, if the GM can handle it more sensitively than H.P. Lovecraft did).

[Flyndaran]

I believe that a large portion, if not a majority of gun related deaths in the U.S., are suicides. While that certainly won't matter when a monster dies from a boat ton of bullets, some real world people have shot themselves multiple times. At least a few such cases involved head shots.

That may be a usable plot point in a specific adventure or two.

[Varyon]

Originally Posted by Flyndaran

I believe that a large portion, if not a majority of gun related deaths in the U.S., are suicides. While that certainly won't matter when a monster dies from a boat ton of bullets, some real world people have shot themselves multiple times. At least a few such cases involved head shots.

That may be a usable plot point in a specific adventure or two.

I was unaware of this, but the results of a quick Google search indicate that, indeed, 60% of US gun deaths (or at least deaths where the gunshot wound was the primary cause of death) were suicides in 2017.

Of course, as OP noted, the problem arises when the characters don’t have time to setup beforehand or cleanup afterward. I’d imagine in cases where they do have such time, they can make it look like a suicide, frame somebody else for the murder, or even just “disappear” the victim in some way.

[acrosome]

Thanks, folks. There's a lot to consider here, actually.

[Ulzgoroth]

Originally Posted by Rupert

Use abrasive paste and a steel bore brush before and after. While the rifling will still be apparent on the bullet, and thus the make of gun might be distinguishable, the scratches on the bullet will be rather different from the ones the barrel will leave on test bullets after such treatment.

Also, note that bullet to gun matching is not an exact science, and in some cases is more wishful thinking than anything else. Use common mass-market over-the-counter ammo in a common firearm, do what I say above (and possibly give the firing pin and extractor a good scrub as well), and this sort of forensics will be quite hard, which is not to say that if you character is already a suspect the evidence won't be used anyway, because being able to say "this guy's gun could have been the one is still useful.

And if the investigators/prosecutors think you make a good suspect, their forensics experts might give them testimony a good bit stronger than that. Regardless of whether the material evidence really justifies that.