The tickle of curiosity. The gasp of discovery. Fingers running across the keyboard.

The tickle of curiosity. The gasp of discovery. Fingers running across a keyboard
Showing posts with label Shotgun. Show all posts
Showing posts with label Shotgun. Show all posts

Wednesday, July 9, 2014

Ballistic Forensics and Firearms Investigations: Was a Gun Used at Your Crime Scene? Information for Writers



Side-by-side comparison of many common pistol ...
(Photo credit: Wikipedia)
Your investigator is combing the crime scene and comes up with some cartridges and a bullet. Hmm can her findings help her tie the bullet found in the injured victim to the gun that was in the villain's car? Let's see what you could plot out.

What does a firearms investigator look for on the gun itself?
* What is the overall condition of the weapon?
* Is the gun capable of being fired? Do all of the parts
   function?
* Were there any modifications made to the gun? Many are illegal.
* The serial number to see if it can be traced to an
   owner.

What if the serial number has been removed?
Restoration of a serial number if someone filed it off is possible. A serial number can't really be filed off to completely remove trace information. In the manufacturing process the act of making the number stamp leaves permanent stress marks in the metal below. An investigator will file the area as smooth as possible then use the metal etcher called Fry's Reagent. This will dissolve the metal and expose the numbers. Because the chemical agent continues to etch the metal surface, the window for being able to see/read the number is short lived and must be watched carefully and photographed. The investigators only get one shot (no pun intended) - so better not have someone interrupt the procedure or your plot line could take a turn - they'll never get the chance back.

What if an investigator finds a bullet or casing?
When an investigator finds:
* tool marks
* firearms
* bullets
* cartridge cases
at a crime scene, they are investigated in much the same way and usually by the same experts.
Blog Link - Tool Mark Forensics

By the way, Firearms examination and ballistics are NOT the same thing

Ballistics is a form of physics that studies the way any object travels -  this could be anything from a soccer ball to a paper airplane. In forensics it usually is referring to bullets and shotgun shells. 



Let's start with some basics:

Investigators will first determine which group of firearms was used.

5 Main Groups of Fire Arms
* Pistols/Handguns (Handgun Information Blog Link)
   `revolver cartridge casing of shot bullet remains in the chamber
   and must be emptied.
   `self loading pistols - ejects the casings
* Rifles (Shotgun and Rifle information Blog Link)
   `single shot
   `double shot
    `semi-automatic
   `automatic
* Shotguns
Cartouche
Cartouche (Photo credit: Wikipedia)
   `They DO NOT shoot
     bullets they shoot 
     buckshot, pellets, or 
     slugs (a slug has a single 
     projectile usually a soft 
     metal like lead that is
     loaded into a shotgun
    shell)
* Machine guns
   `automatic weapons
   `fed ammo from a magazine or a belt
   `powerful recoil
   `get very hot so they need to be mounted on a stand
*Submachine Guns
   `Fully automatic
   `Can be hand held


The Investigators will also look at bullets recovered from a crime scene or a victim's body and/or the casings to see if a bullet came from the barrel of a certain type of gun.

The Gun Barrel
* a barrel of a gun is produced by hollowing out a solid metal bar. 
   The drill that does this will leave random tool marks on the inside.
    After the barrel is hollowed out then a series of 
   grooves are made to the inside these are called rifling.
* The flat places are called lands
* The space between them are called grooves


This is an image of a 35 remington caliber, mi...
This is an image of a 35 remington caliber, microgroove rifled barrel manufactured by the marlin firearms company. it shows a 20 land and groove barrel with a right hand twist. The image was taken with a Nikon DX1 camera using f22 and a 1/30 ss. The bore of the barrel was lighted with a standard bore light. --Rickochet 12:59, 9 July 2006 (UTC) (Photo credit: Wikipedia)

Now, the verb rifling means the spin that is put on a flying object. A baseball player, for example, will rifle the ball to make it spin so that the object stays on a true trajectory. (HINT: Shotgun barrels are NOT rifled they are smooth-bore)

When a bullet is fired through the barrel the bullet takes on the impression of the barrel's rifling. The lands on the barrel will make grooves on the bullet and the grooves will make raised spaces. Think of this like an old-time photographic negative.

Different manufacturers use different rifling specifications. For example: all Smith and Wesson .32 caliber revolvers have 5 lands and 5 grooves that twist right. Maybe the make of the gun twists left or has 9 lands. A firearms investigator can then look at the bullet and narrow down the gun manufacturer.

Caliber - the inside diameter measurement of a guns barrel measured between the lands (raised part of the rifling). We see these written as either hundredths of an inch or in mm.

Gauge - the measurement of a shotgun barrel (there's math formula for this that has to do with number of pellets that can fit into a pound)

The size of the bullet that was shot therefore can help determine:
1) Was it a smooth-bore or a rifled gun
2) What size barrel did the gun have? was it a .22? a 9mm? a .45?

Video Quick Study (6:34) Demonstration of a FBI firearm investigation

Type of gun is class evidence. It cannot tie a gun to a specific crime. But microscopic anomalies in production as well as use will make one gun barrel specifically different from another - as different as fingerprints. So when the bullet travels through the barrel the lands and grooves as well as the microscopic anomalies get transferred. Now they can tie a specific bullet to a specific gun. To do this
* The gun in question is examined in the lab
* The same kind of bullet is used (see bullet tutorial for different
   kinds of bullets that could be chosen for a gun such as hollow
   point FMJ Blog Link) from the same manufacturer.
* The bullet is fired into a test tank
* The crime scene evidentiary bullet is compared to the test bullet
    by computers or under high-powered microscopes
* Full metal jacketed bullets tend to be easiest to handle with more
   consistent striated details.

Video Quick Study (1:21) of a bullet being fired.
Video Quick Study (2:28) NCSTL does a quick overview of firearm investigation
Video Quick Study (8:12) Showing a test tank for gathering evidence of the striations of a gun in question

The ATF developed the Integrated Ballistics Identification System (IBIS)
IBIS is the computer system that can match the known barrel identification markings and match them to a bullet's markings. In this way various crimes can be linked to a single gun.
Video Quick Study (1:43)

English: Badge of the Bureau of Alcohol, Tobac...
 (Photo credit: Wikipedia)

Video Quick Study (4:29)
Video Quick Study (7:11)

This computer is not the "silver bullet" Once the computer finds a match it still has to be manually examined by an investigator - your investigation team
skipped this step? Might come
out in your court case scene - did
you want the perp to walk?

Video Quick Study (8:57) This shows you the holes that you can use in your plot, including how to change the barrel quickly and easily by just cleaning it with an abrasive cleaning product and thus change the microscopic tool marks. (Fair warning - NRA sponsored so this video does have it's own agenda)

Now on to the spent bullet and shell cases

The cases on a scene often have the manufacturer information stamped right on them. They may also have the markings from the firing pin (the tiny piece that hits the end of the round to send it down the barrel).

If a bullet or casing is found at the scene the investigator has to take great care not to damage any of the microscopic markings on the evidence. This means they may have to cut a section out of a wall if the bullet is embedded to take the whole thing back to the lab for the investigators to work on.

The gun, casings, and bullets will all be checked for fingerprints as well. (fingerprint article Blog Link). They will also look for trace evidence such as lint or hair.

And finally, a look at propellants and primers:
Inside of a round there is the bullet, the propellant and at the bottom a little bit of primer. The firing pin strikes the primer, igniting the propellant and forcing the round down the barrel of the gun. 


7N1 bullet cross sections
7N1 bullet cross sections (Photo credit: Wikipedia)

GSR - Gunshot residue
* Partially burned and unburned powder
* Soot
* Lead
* Vapors




Because GSR comes out in a geometric configuration as it leaves the barrel, if the target was within a yard of the gunshot, then investigators can determine how far away the gun was held.

GSR gets everywhere - on the victim on the shooter and in the environment (lead, barium, and antimony). Can be removed with soap and water.

.40S&W cartridge next to expanded hollow point...
.40S&W cartridge next to expanded hollow point bullet. (Photo credit: Wikipedia)



Thank you so much for stopping by. And thank you for your support. When you buy my books, you make it possible for me to continue to bring you helpful articles and keep ThrillWriting free and accessible to all.


Sunday, June 15, 2014

Dynamic Handguns and Shooting in a Structure: Information for Writers Prt 1 - Plotting Gems



graphic found on Facebook
This blog article is based on my experience at an all-day dynamic gun training class that I took at 
Nottoway Wildlife Association, LINK  called "Personal Protection in the Home," following NRA curriculum. 

These are the same folks who taught me about rifles in this article: BLOG LINK

You are writing a kick ass heroine. Woot! And while everyone loves a beautiful, smart, effective heroine, and I have one as the main character in my Lynx series, it also adds dimension and reality if she struggles a little bit. One of my writing coaches told me that if things are going well for your heroine, you're writing it wrong. Your girl should be constantly struggling.

Well if I were a template for a heroine in a dynamic gun situation, believe me there was a whole lot of struggling going on. 

Before your heroine even brings a gun into her home she:

* Understands that using a gun or any lethal weapon
   is a tool of last resort - though your heroine doesn't believe this
   standard applies during a zombie apocalypse.

* Understands that gun laws and her decision making is
   based on locality; she should know her laws and have made her
   decisions in advance. How your plot advances depends on the
   reality of those laws.

The focus of this first blog in the three-part Dynamic Handgun series is take-away plotting gems that I picked up through hands on practice and lecture.


Found on Facebook


Things I learned: Or, Why your heroine can't go out and buy a gun today, and blow away the bad guy who jumps out of her closet with a machete in his hands tomorrow.




* Firing on a range and
Indoor Shooting Range at Sarasota, Florida, US...
 (Photo credit: Wikipedia)
   dynamic 
   (moving/situational) firing
   are vastly different.
* Firing on the fly without
   lining up the sites and
   having time to
   check stance, breathing, etc.
   will definitely effect your
   heroine's ability to hit the
   mark dead center. 
   Her goal is merely center-
   mass. As a range shooter, I
   hit bulls' eyes. That day? 
   Eh, not so much.

* I am a dancer/MA fighter; you'd think that I had control over my
   body. When my focus was on the "bad guy" also known as the
   little piece of paper in front of me, my coordination was off. Way
   off.
   
   Watch this video that was taken on the archery range.





   Here you can see the technique while focused on a single task.
   My right elbow is down and back. Then I was asked to perform a
   memory task and a speech task with the second shot. Even
   moving with plenty of time and deliberation, you can see my
   practiced body mechanics shift; my right elbow went above
   my head. The point here being - your heroine must practice
   situational, all components put together, tactics if you are going to
   write her a successful outcome. Doing it first time on-the-fly
   just won't fly with your readers who know anything about tactical
   shooting.

   * Past injuries can effect your character's ability to move fluidly
   into certain dynamic poses. For example, as I tried to follow the
   instructions to go down on my right knee, I felt like and old rusted
   gate. My ACL (central knee ligament) is made from a cadaver
   ligament after a fight that did not end in my favor. Who knew this
   would impact anything? In MA practice and dancing, I simply
   don't make that move. For me everything was very crunchy
   granola, and I lost my balance on the way down. So think about
   your character's past injuries and how they could effect her
   present-time shooting scenarios. Did something happen in the past
   that could trip her up now? Remember, nothing should come easy
   for her

   Brian Coates, whom you will see in the ThrillWriting 
   inset video at the bottom of this article, is a U.S. Marine Corp.
   veteran. He moved into place and dropped to his knee smoothly.
   (I'd say gracefully, but I think that would paint the wrong 
   picture.) 

   Video Quick Study (3:46) Shooting on the move

   Practice makes perfect. Practice on this specific move - not just a 
   generally fit/sportive heroine. While being an active person might 
   make the learning curve quicker, there will still be a learning
   curve.

* In my mind, switching to non-dominant hand shooting was no
   big deal. When I was actually asked to perform the task, I had to
   stop and look at my gun and figure out how to change my
   fingering, my left finger on the trigger felt really odd and pulling
   the trigger with my left index finger felt even odder. Did your
   heroine sustain an injury to her dominant arm/hand
   necessitating a switch? It's not going to be as easy or effective as 
   it is in the movies unless she trained this action.


English: Naval Station Everett, Wash (Jan. 29,...
) (Photo credit: Wikipedia)
* Eyesight matters. I know
   you're thinking, no duh. But
   what if your heroine wears
   glasses or contacts? Does
   she have time to grab her
   glasses and her gun? 

   What if there is low light/no
   light? Did she practice 
   aiming with her eyes 
   closed? Does she have 
   a light attached to her gun? 
   A laser?

   Consider not  just eyesight
   but visual dexterity. 
   How quickly can your
   heroine spot and decipher a 
   potential threat especially 
   in an adrenaline impacted 
   situation? This is a trained
   response. Maybe not 
   necessarily combat training
   but some discrimination training

   Did her past job/conditioning make certain eye patterns difficult? 
   Let me give you and example: 
   One of our tasks was to not aim the gun with sights but merely to
   look at the center of the target and pull the trigger. My paper had 
   bullet holes neatly placed all the way around the outside of the
   target circle not a single shot made it to the inside. 


Image found publicly on Facebook
I feel his pain

   When my instructors talked to me about focus, I realized that I 
   could not perform this task because I have done neuro-plasticity 
   training that required me to look at a center point and focus on
   the periphery. Something I will now train to overcome. Gamers
   might have this kind of reaction and certain sports. 


Image copied from Facebook


* While revolvers are predictably reliable, automatics fail. My gun
   needed oil, so it failed quite a bit. (Lesson learned.)
   ` Stove pipe - when a bullet sticks straight up in the chamber
   ` Two bullets in the chamber
     Video Quick Study (10:37) malfunctions and clearing
     instructions notice he says to practice at home with snap caps.
     Your heroine must practice to be effective.






graphic found on Facebook

* They ran a drill that demonstrated a knife wielding villain can get
   to and injure your heroine before she could get a shot off (with
   the gun already in her hands). This might be good news for a 
   heroine who attempts to flee a gun scene. It might be bad news to
   your heroine if she is all that's standing between the bad guy and 
   the future of the world as we know it.

* Being shot is not as effective as one might be lead to believe by
   watching video games, movies and the like.
   ^ It is typically not bloody or even visible. If you need a bloody
     crime scene try a knife. (Homicide Scenes Blog Link, Blood
     Spatter Blog Link)
   ^ The person does not blow backwards as if there was a bomb.
     They collapse if the bullet was well placed like a shot to the
     head.
   ^ Often the person who is experiencing adrenaline will not even
     realize they've been shot ( read about that under scar story at
     bottom of this interview Blog Link)
   ^ Multiple, well-placed shots must occur in order to down your
      villain.
   ^ It will take several seconds for the impact of those shots to take
     effect. In those seconds the villain is still functioning and can
     still harm your heroine.
   ^ Your villain's physical response will be effected by drugs or
      alcohol use. (Illegal Drugs 101 - choosing a drug for your
      villain Blog Link)
    ^DOWN DOES NOT MEAN OUT
     - was he wearing a bullet-proof vest and merely stunned?
     - is he faking the collapse so that he can get your heroine to
       lower her guard?
     - Have your heroine cover the guy with her gun, stay vigilant,
       and wait for the police. She shouldn't go up and frisk him - he
       may grab her, take her down, and take her weapon --or maybe
       that's what you want to happen next. Or maybe she's in a
       remote area with no hope of help. Now she has to make some
       darned hard choices.

* Knowing that an attack happens quickly, and your character
   needs to get her bullets in even more quickly, I shot my entire 
   extended cartridge (16 count) of bullets as fast as I could with 
   some semblance of hitting central mass. I knew I was being taped 
   and therefore could time it. 10 seconds and I was empty. I was 
   fortunate that I didn't have any malfunctions while firing those 
   rounds.


Brian Coates demonstrating a behind barrier strategy discussed in
Prt 2 of Dynamic Handguns. Fiona Quinn emptying her mag.

You were not a very benevolent author and decided that your heroine would not be attacked by one but several assailants all at once. What's your girl to do to save her skin?
* She should engage the most hazardous threat first. 
   Things which might inform her assessment include:
   ^ How close are the attackers to her and which is closest
   ^ What kinds of weapon are they wielding? 
   ^ How fast are the attackers coming at her?
      We know that the police with all of their training only have a
       20% impact rate. And we know that you can survive and act
       after being hit by a bullet. Since the guy with the machete is
       barreling towards her, she might chance the bullet hit to stop 
       the machete-swinger.
* How many bullets does she have? If your girl is unloading on
   thing-one, then thing-two ran round the corner, she's left with
   a not particularly useful empty gun
   Another strategy would be to try to put a
   bullet in each of the ogres and then assess. Was she successful?
   Yes? Call the police and wait. They're still attacking? Shoot
   another round into each and so forth.
* Remember, even the best of the best get tunnel vision and train
   strategies to prevent this from happening. While she has the ogre
   in her sights his troll partner could be sneaking up behind her and
   she'd never know he was swinging his club - lights out. 


Some of my articles you might want to review along with this information -

About guns:
Found on Facebook
Bullet Tutorial
Choosing a Handgun
Shotguns and Rifles
Shooter Simulation 
       (tunnel vision)
Carrying Concealed (interview)

About forethought/preparation:
Home Invasion - Hard v. Soft Target
Home Invasion - Setting Up a Safe Room & Creating an Escape Route



Thank you so much for stopping by. And thank you for your support. When you buy my books, you make it possible for me to continue to bring you helpful articles and keep ThrillWriting free and accessible to all.


This article was informed by the NRA Guide to the Basics of Personal Protection in the Home (2000)
As always, this is a non-political site that is geared to help writers write it right. I am presenting information to help develop fictional characters and fictional scenes. In no way am I advocating any position or personal decision.
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