William E. Demuth II

Chair, AFTE Standardization and Training Committee

Training Coordinator, Illinois State Police, Division of 

Forensic Services, Forensic Sciences Command, 

Statewide Training Program
Current Technology Used in the Laboratory – William E. Demuth II

Goals

 The purpose of this presentation is to give the nonFirearms Examiner an introduction to the measurement 

technology found in the typical modern Firearms Unit.
Current Technology Used in the Laboratory – William E. Demuth II

Goals

 The purpose of this presentation is to give the nonFirearms Examiner an introduction to the measurement 

technology found in the typical modern Firearms Unit.

 This will be accomplished by discussing:
Current Technology Used in the Laboratory – William E. Demuth II

Goals

 The purpose of this presentation is to give the nonFirearms Examiner an introduction to the measurement 

technology found in the typical modern Firearms Unit.

 This will be accomplished by discussing:

 The types of instrumentation found in the section
Current Technology Used in the Laboratory – William E. Demuth II

Goals

 The purpose of this presentation is to give the nonFirearms Examiner an introduction to the measurement 

technology found in the typical modern Firearms Unit.

 This will be accomplished by discussing:

 The types of instrumentation found in the section

 Microscopes
Current Technology Used in the Laboratory – William E. Demuth II

Goals

 The purpose of this presentation is to give the nonFirearms Examiner an introduction to the measurement 

technology found in the typical modern Firearms Unit.

 This will be accomplished by discussing:

 The types of instrumentation found in the section

 Microscopes

 Measuring Devices
Current Technology Used in the Laboratory – William E. Demuth II

Goals

 The purpose of this presentation is to give the nonFirearms Examiner an introduction to the measurement 

technology found in the typical modern Firearms Unit.

 This will be accomplished by discussing:

 The types of instrumentation found in the section

 Microscopes

 Measuring Devices

 Mass/weight, force
Current Technology Used in the Laboratory – William E. Demuth II

Goals

 The purpose of this presentation is to give the nonFirearms Examiner an introduction to the measurement 

technology found in the typical modern Firearms Unit.

 This will be accomplished by discussing:

 The types of instrumentation found in the section

 Microscopes

 Measuring Devices

 Mass/weight, force

 Dimensional
Current Technology Used in the Laboratory – William E. Demuth II

Goals

 The purpose of this presentation is to give the nonFirearms Examiner an introduction to the measurement 

technology found in the typical modern Firearms Unit.

 This will be accomplished by discussing:

 The types of instrumentation found in the section

 Microscopes

 Measuring Devices

 Mass/weight, force

 Dimensional

 The types of measurements collected
Current Technology Used in the Laboratory – William E. Demuth II

Goals

 The purpose of this presentation is to give the nonFirearms Examiner an introduction to the measurement 

technology found in the typical modern Firearms Unit.

 This will be accomplished by discussing:

 The types of instrumentation found in the section

 Microscopes

 Measuring Devices

 Mass/weight, force

 Dimensional

 The types of measurements collected

 Purpose
Current Technology Used in the Laboratory – William E. Demuth II

Goals

 The purpose of this presentation is to give the nonFirearms Examiner an introduction to the measurement 

technology found in the typical modern Firearms Unit.

 This will be accomplished by discussing:

 The types of instrumentation found in the section

 Microscopes

 Measuring Devices

 Mass/weight, force

 Dimensional

 The types of measurements collected

 Purpose

 Possible issues
Current Technology Used in the Laboratory – William E. Demuth II

Microscopes

 Stereomicroscope

“An optical instrument, which provides three dimensional 

viewing of an object through paired objectives and 

eyepieces. Some models share a common main objective”

AFTE Glossary, 5th Edition
Current Technology Used in the Laboratory – William E. Demuth II

Microscopes

 Stereomicroscope
Current Technology Used in the Laboratory – William E. Demuth II

Microscopes

 Stereomicroscope

 Provides magnification
Current Technology Used in the Laboratory – William E. Demuth II

Microscopes

 Stereomicroscope

 Provides magnification

 Provides stereoscopic view
Current Technology Used in the Laboratory – William E. Demuth II

Microscopes

 Stereomicroscope

 Provides magnification

 Provides stereoscopic view 

 Allows for less restricted manipulation of items
Current Technology Used in the Laboratory – William E. Demuth II

Microscopes

 Stereomicroscope

 Provides magnification

 Provides stereoscopic view 

 Allows for less restricted manipulation of items

 May be used in conjunction with standard measuring 

devices
Current Technology Used in the Laboratory – William E. Demuth II

Microscopes

 Stereomicroscope

 Provides magnification

 Provides stereoscopic view 

 Allows for less restricted manipulation of items

 May be used in conjunction with standard measuring 

devices

 Bridges the gap between visual examination of items 

and the use of the comparison microscope
Current Technology Used in the Laboratory – William E. Demuth II

Microscopes

 Stereomicroscope

 Greenough
Current Technology Used in the Laboratory – William E. Demuth II

Microscopes

 Stereomicroscope

 Greenough

 Two identical optical 

systems slightly offset to 

create the stereoscopic 

effect
Current Technology Used in the Laboratory – William E. Demuth II

Microscopes

 Stereomicroscope

 Greenough

 Two identical optical 

systems slightly offset to 

create the stereoscopic 

effect

 Rugged
Current Technology Used in the Laboratory – William E. Demuth II

Microscopes

 Stereomicroscope

 Greenough

 Two identical optical 

systems slightly offset to 

create the stereoscopic 

effect

 Rugged

 Compact
Current Technology Used in the Laboratory – William E. Demuth II

Microscopes

 Stereomicroscope

 Greenough

 Two identical optical 

systems slightly offset to 

create the stereoscopic 

effect

 Rugged

 Compact

 Relatively inexpensive
Current Technology Used in the Laboratory – William E. Demuth II

Microscopes

 Stereomicroscope

 Common Main Objective 

(CMO)

 Image courtesy of Nikon’s MicrscopyU
Current Technology Used in the Laboratory – William E. Demuth II

Microscopes

 Stereomicroscope

 Common Main Objective 

(CMO)

 Single, large diameter 

objective lens
Current Technology Used in the Laboratory – William E. Demuth II

Microscopes

 Stereomicroscope

 Common Main Objective 

(CMO)

 Single, large diameter 

objective lens

 Collimated light path 

 Accessories can be 

introduced into the 

infinity space with little to 

no image aberrations

 Image courtesy of Nikon’s MicrscopyU
Current Technology Used in the Laboratory – William E. Demuth II

Microscopes

 Stereomicroscope

 Common Main Objective 

(CMO)

 Single, large diameter 

objective lens

 Collimated light path 

 Accessories can be 

introduced into the 

infinity space with little to 

no image aberrations 

 Can cost several times as 

much as a Greenough-type

Image courtesy of Nikon’s MicrscopyU
Current Technology Used in the Laboratory – William E. Demuth II

 Image courtesy of Nikon’s MicrscopyU
Current Technology Used in the Laboratory – William E. Demuth II

Microscopes

 Comparison Microscope

“ Essentially two microscopes connected to an optical 

bridge which allows the viewer to observe two objects 

simultaneously with the same degree of magnification. 

This instrument can have a monocular or binocular 

eyepiece. Sometimes referred to as a COMPARISON 

MACROSCOPE.”

AFTE Glossary, 5th Edition
Current Technology Used in the Laboratory – William E. Demuth II

Microscopes

 Comparison Microscope
Current Technology Used in the Laboratory – William E. Demuth II

Microscopes

 Comparison Microscope
Current Technology Used in the Laboratory – William E. Demuth II

Microscopes

 Comparison Microscope

 Instrument by which fired 

ammunition components are 

directly compared to one 

another
Current Technology Used in the Laboratory – William E. Demuth II

Bullets Fired from the Same Barrel
Current Technology Used in the Laboratory – William E. Demuth II

Cartridge Cases Fired in the Same Firearm
Current Technology Used in the Laboratory – William E. Demuth II

Microscopes

 Comparison Microscope

 Instrument by which fired 

ammunition components are 

directly compared to one 

another

 Has remained largely 

unchanged since it’s 

introduction
Current Technology Used in the Laboratory – William E. Demuth II

Microscopes

 Comparison Microscope

 Instrument by which fired 

ammunition components are 

directly compared to one 

another

 Has remained largely 

unchanged since it’s 

introduction

 Magnification is dependent 

on setup
Current Technology Used in the Laboratory – William E. Demuth II

Microscopes

 Comparison Microscope

 Instrument by which fired 

ammunition components are 

directly compared to one 

another

 Has remained largely 

unchanged since it’s 

introduction

 Magnification is dependent 

on setup

 Typically 5x or 10x oculars
Current Technology Used in the Laboratory – William E. Demuth II

Microscopes

 Comparison Microscope

 Instrument by which fired 

ammunition components are 

directly compared to one 

another

 Has remained largely unchanged 

since it’s introduction

 Magnification is dependent on 

setup

 Typically 5x or 10x oculars

 Objectives typically range from .5x 

to 4x
Current Technology Used in the Laboratory – William E. Demuth II

Microscopes

 Comparison Microscope

 Instrument by which fired 

ammunition components are 

directly compared to one 

another

 Has remained largely unchanged 

since it’s introduction

 Magnification is dependent on 

setup

 Typically 5x or 10x oculars

 Objectives typically range from .5x 

to 4x

 Total magnification from 2.5x to 

40x
Current Technology Used in the Laboratory – William E. Demuth II

Microscopes

 Comparison Microscope

 Instrument by which fired 

ammunition components are 

directly compared to one another

 Has remained largely unchanged 

since it’s introduction

 Magnification is dependent on 

setup

 Typically 5x or 10x oculars

 Objectives typically range from .5x to 

4x

 Total magnification from 2.5x to 40x

 May be used in conjunction with 

standard measuring devices
Current Technology Used in the Laboratory – William E. Demuth II

 Powder Balance

Measuring Devices – Weight/Mass, Force
Current Technology Used in the Laboratory – William E. Demuth II

 Powder Balance

 Mass of bullet

Measuring Devices – Weight/Mass, Force
Current Technology Used in the Laboratory – William E. Demuth II

 Powder Balance

 Mass of bullet

 Aid in caliber determination

Measuring Devices – Weight/Mass, Force
Current Technology Used in the Laboratory – William E. Demuth II

 Powder Balance

 Mass of bullet

 Aid in caliber determination

 Mass of powder

Measuring Devices – Weight/Mass, Force
Current Technology Used in the Laboratory – William E. Demuth II

 Powder Balance

 Mass of bullet

 Aid in caliber determination

 Mass of powder

 Downloading cartridges

Measuring Devices – Weight/Mass, Force
Current Technology Used in the Laboratory – William E. Demuth II

 Powder Balance

 Mass of bullet

 Aid in caliber determination

 Mass of powder

 Downloading cartridges

 Reloaded/handloaded

cartridges

Measuring Devices – Weight/Mass, Force
Current Technology Used in the Laboratory – William E. Demuth II

 Trigger Pull

Measuring Devices – Weight/Mass, Force
Current Technology Used in the Laboratory – William E. Demuth II

 Trigger Pull

 An indication of how much force needs to be applied to 

the trigger of a firearm to cause it to fire

Measuring Devices – Weight/Mass, Force
Current Technology Used in the Laboratory – William E. Demuth II

 Trigger Pull

 An indication of how much force needs to be applied to 

the trigger of a firearm to cause it to fire

 A large portion of the community represents this in 

terms of pounds

Measuring Devices – Weight/Mass, Force
Current Technology Used in the Laboratory – William E. Demuth II

 Trigger Pull

 An indication of how much force needs to be applied to 

the trigger of a firearm to cause it to fire

 A large portion of the community represents this in 

terms of pounds

 Consistent with the firearms manufacturing industry

Measuring Devices – Weight/Mass, Force
Current Technology Used in the Laboratory – William E. Demuth II

 Trigger Pull

 An indication of how much force needs to be applied to 

the trigger of a firearm to cause it to fire

 A large portion of the community represents this in 

terms of pounds

 Consistent with the firearms manufacturing industry

 Product literature tends to report in these terms

Measuring Devices – Weight/Mass, Force
Current Technology Used in the Laboratory – William E. Demuth II

 Trigger Pull

 An indication of how much force needs to be applied to 

the trigger of a firearm to cause it to fire

 A large portion of the community represents this in 

terms of pounds

 Consistent with the firearms manufacturing industry

 Product literature tends to report in these terms

 Relatively easy to determine if the firearm is in the “normal” 

range

Measuring Devices – Weight/Mass, Force
Current Technology Used in the Laboratory – William E. Demuth II

 Trigger Pull

 An indication of how much force needs to be applied to 

the trigger of a firearm to cause it to fire

 A large portion of the community represents this in 

terms of pounds

 Consistent with the firearms manufacturing industry

 Product literature tends to report in these terms

 Relatively easy to determine if the firearm is in the “normal” 

range

 Weight is an easier term for most jurors to understand

Measuring Devices – Weight/Mass, Force
Current Technology Used in the Laboratory – William E. Demuth II

 Trigger Pull

 An indication of how much force needs to be applied to the 

trigger of a firearm to cause it to fire

 A large portion of the community represents this in terms of 

pounds

 Consistent with the firearms manufacturing industry

 Product literature tends to report in these terms

 Relatively easy to determine if the firearm is in the “normal” range

 Weight is an easier term for most jurors to understand

 Some agencies may use this information to form a conclusion 

with regards to accidental/unintentional shooting cases

Measuring Devices – Weight/Mass, Force
Current Technology Used in the Laboratory – William E. Demuth II

 Arsenal weights

Measuring Devices – Weight/Mass, Force
Current Technology Used in the Laboratory – William E. Demuth II

 Arsenal weights

 Increasing amounts of weight 

added until trigger releases 

sear

Measuring Devices – Weight/Mass, Force
Current Technology Used in the Laboratory – William E. Demuth II

 Arsenal weights

 Increasing amounts of weight 

added until trigger releases 

sear

 Repeated to determine 

consistency

Measuring Devices – Weight/Mass, Force
Current Technology Used in the Laboratory – William E. Demuth II

 Arsenal weights

 Increasing amounts of weight 

added until trigger releases 

sear

 Repeated to determine 

consistency

 Gives results on a par with the 

firearms manufacturing 

industry

Measuring Devices – Weight/Mass, Force
Current Technology Used in the Laboratory – William E. Demuth II

 Arsenal weights

 Increasing amounts of weight 

added until trigger releases 

sear

 Repeated to determine 

consistency

 Gives results on a par with the 

firearms manufacturing 

industry 

 Momentum not considered in 

results

Measuring Devices – Weight/Mass, Force
Current Technology Used in the Laboratory – William E. Demuth II

 Arsenal weights

 Increasing amounts of weight 

added until trigger releases sear

 Repeated to determine 

consistency

 Gives results on a par with the 

firearms manufacturing 

industry 

 Momentum not considered in 

results

 Poor technique yields poor 

results

Measuring Devices – Weight/Mass, Force
Current Technology Used in the Laboratory – William E. Demuth II

 Spring gauge

Measuring Devices – Weight/Mass, Force
Current Technology Used in the Laboratory – William E. Demuth II

 Spring gauge

 Increasing amounts of 

pressure applied until trigger 

releases sear

Measuring Devices – Weight/Mass, Force
Current Technology Used in the Laboratory – William E. Demuth II

 Spring gauge

 Increasing amounts of 

pressure applied until trigger 

releases sear

 Repeated to determine 

consistency

Measuring Devices – Weight/Mass, Force
Current Technology Used in the Laboratory – William E. Demuth II

 Spring gauge

 Increasing amounts of 

pressure applied until trigger 

releases sear

 Repeated to determine 

consistency

 Gives results on a par with the 

firearms manufacturing 

industry

Measuring Devices – Weight/Mass, Force
Current Technology Used in the Laboratory – William E. Demuth II

 Spring gauge

 Increasing amounts of 

pressure applied until trigger 

releases sear

 Repeated to determine 

consistency

 Gives results on a par with the 

firearms manufacturing 

industry 

 Momentum not considered in 

results

Measuring Devices – Weight/Mass, Force
Current Technology Used in the Laboratory – William E. Demuth II

 Spring gauge

 Increasing amounts of pressure 

applied until trigger releases 

sear

 Repeated to determine 

consistency

 Gives results on a par with the 

firearms manufacturing 

industry 

 Momentum not considered in 

results

 Poor technique yields poor 

results

Measuring Devices – Weight/Mass, Force
Current Technology Used in the Laboratory – William E. Demuth II

 Force gauge

Measuring Devices – Weight/Mass, Force
Current Technology Used in the Laboratory – William E. Demuth II

 Force gauge

 Automated models that recognize when the trigger 

“breaks”

Measuring Devices – Weight/Mass, Force
Current Technology Used in the Laboratory – William E. Demuth II

 Force gauge

 Automated models that recognize when the trigger 

“breaks”

 Measurements given in Joules or Inch-Pound Force

Measuring Devices – Weight/Mass, Force
Current Technology Used in the Laboratory – William E. Demuth II

Measuring Devices - Dimensional

 Rulers, Tape Measures, 

Machinist’s Scales, etc.
Current Technology Used in the Laboratory – William E. Demuth II

Measuring Devices - Dimensional

 Rulers, Tape Measures, 

Machinist’s Scales, etc.

 Used for simple, straight-line 

dimensions on firearms and 

attachments
Current Technology Used in the Laboratory – William E. Demuth II

Measuring Devices - Dimensional

 Rulers, Tape Measures, 

Machinist’s Scales, etc.

 Used for simple, straight-line 

dimensions on firearms and 

attachments

 Overall length of firearms
Current Technology Used in the Laboratory – William E. Demuth II

Measuring Devices - Dimensional

 Rulers, Tape Measures, 

Machinist’s Scales, etc.

 Used for simple, straight-line 

dimensions on firearms and 

attachments

 Overall length of firearms

 Barrel length of firearms
Current Technology Used in the Laboratory – William E. Demuth II

Measuring Devices - Dimensional

 Rulers, Tape Measures, 

Machinist’s Scales, etc.

 Used for simple, straight-line 

dimensions on firearms and 

attachments

 Overall length of firearms

 Barrel length of firearms

 May be inexpensive, simple 

devices
Current Technology Used in the Laboratory – William E. Demuth II

Measuring Devices - Dimensional

 Rulers, Tape Measures, 

Machinist’s Scales, etc.

 Used for simple, straight-line 

dimensions on firearms and 

attachments

 Overall length of firearms

 Barrel length of firearms

 May be inexpensive, simple 

devices

 May be special-purpose devices
Current Technology Used in the Laboratory – William E. Demuth II

Measuring Devices - Dimensional

 Rulers, Tape Measures, Machinist’s 

Scales, etc.

 Used for simple, straight-line 

dimensions on firearms and 

attachments

 Overall length of firearms

 Barrel length of firearms

 May be inexpensive, simple devices

 May be special-purpose devices

 Should be certified and traceable to a 

NIST standard
Current Technology Used in the Laboratory – William E. Demuth II

Measuring Devices - Dimensional

 Rulers, Tape Measures, Machinist’s 

Scales, etc.

 Used for simple, straight-line 

dimensions on firearms and 

attachments

 Overall length of firearms

 Barrel length of firearms

 May be inexpensive, simple devices

 May be special-purpose devices

 Should be certified and traceable to a 

NIST standard

 Used for critical measurements
Current Technology Used in the Laboratory – William E. Demuth II

 Barrel Length and Overall Length

 The term "short-barreled shotgun" means a shotgun 

having one or more barrels less than eighteen inches in 

length and any weapon made from a shotgun (whether 

by alteration, modification, or otherwise) if such 

weapon as modified has an overall length of less than 

twenty-six inches.

Measuring Devices - Dimensional
Current Technology Used in the Laboratory – William E. Demuth II

 Barrel Length and Overall Length

 The term "short-barreled shotgun" means a shotgun 

having one or more barrels less than eighteen inches in 

length and any weapon made from a shotgun (whether 

by alteration, modification, or otherwise) if such 

weapon as modified has an overall length of less than 

twenty-six inches.

 The term "short-barreled rifle"means a rifle having one 

or more barrels less than sixteen inches in length and 

any weapon made from a rifle (whether by alteration, 

modification, or otherwise) if such weapon, as modified, 

has an overall length of less than twenty-six inches.

Measuring Devices - Dimensional
Current Technology Used in the Laboratory – William E. Demuth II

 Barrel Length and Overall Length

Measuring Devices - Dimensional
Current Technology Used in the Laboratory – William E. Demuth II

 Barrel Length and Overall Length

 An example of a “critical measurement”

Measuring Devices - Dimensional
Current Technology Used in the Laboratory – William E. Demuth II

 Barrel Length and Overall Length

 An example of a “critical measurement”

 One of the few measurements that is included in the 

report

Measuring Devices - Dimensional
Current Technology Used in the Laboratory – William E. Demuth II

 Barrel Length and Overall Length

 An example of a “critical measurement”

 One of the few measurements that is included in the 

report

 Additional charges may be leveled based on the 

measurements collected and reported

Measuring Devices - Dimensional
Current Technology Used in the Laboratory – William E. Demuth II

 Barrel Length and Overall Length

 An example of a “critical measurement”

 One of the few measurements that is included in the 

report

 Additional charges may be leveled based on the 

measurements collected and reported

 Use of certified measuring devices

Measuring Devices - Dimensional
Current Technology Used in the Laboratory – William E. Demuth II

 Barrel Length and Overall Length

 An example of a “critical measurement”

 One of the few measurements that is included in the 

report

 Additional charges may be leveled based on the 

measurements collected and reported

 Use of certified measuring devices

 Calculation of Measurement Uncertainty

Measuring Devices - Dimensional
Current Technology Used in the Laboratory – William E. Demuth II

Measuring Devices - Dimensional

 Micrometer
Current Technology Used in the Laboratory – William E. Demuth II

Measuring Devices - Dimensional

 Micrometer

 Used for dimensional measurements 

on fired evidence
Current Technology Used in the Laboratory – William E. Demuth II

Measuring Devices - Dimensional

 Micrometer

 Used for dimensional measurements 

on fired evidence

 Determining caliber for cartridge cases 

with inadequate/misleading headstamp

markings
Current Technology Used in the Laboratory – William E. Demuth II

Measuring Devices - Dimensional

 Micrometer

 Used for dimensional measurements 

on fired evidence

 Determining caliber for cartridge cases 

with inadequate/misleading headstamp 

markings

 Caliber of fired bullets
Current Technology Used in the Laboratory – William E. Demuth II

Measuring Devices - Dimensional

 Micrometer

 Used for dimensional measurements 

on fired evidence

 Determining caliber for cartridge cases 

with inadequate/misleading headstamp 

markings

 Caliber of fired bullets

 Diameter of bearing surface
Current Technology Used in the Laboratory – William E. Demuth II

Measuring Devices - Dimensional

 Micrometer

 Used for dimensional measurements 

on fired evidence

 Determining caliber for cartridge cases 

with inadequate/misleading headstamp 

markings

 Caliber of fired bullets

 Diameter of bearing surface

 Width of land and groove impressions
Current Technology Used in the Laboratory – William E. Demuth II

Measuring Devices - Dimensional

 Micrometer

 Used for dimensional measurements 

on fired evidence

 Determining caliber for cartridge cases 

with inadequate/misleading headstamp 

markings

 Caliber of fired bullets

 Diameter of bearing surface

 Width of land and groove impressions

 When used in conjunction with stereo 

or comparison microscope
Current Technology Used in the Laboratory – William E. Demuth II

Measuring Devices - Dimensional

 Micrometer

 Used for dimensional measurements 

on fired evidence

 Determining caliber for cartridge cases 

with inadequate/misleading headstamp 

markings

 Caliber of fired bullets

 Diameter of bearing surface

 Width of land and groove impressions

 When used in conjunction with stereo 

or comparison microscope

 Various levels of quality and readout
Current Technology Used in the Laboratory – William E. Demuth II

Measuring Devices - Dimensional

 Micrometer

 Used for dimensional measurements on 

fired evidence

 Determining caliber for cartridge cases with 

inadequate/misleading headstamp markings

 Caliber of fired bullets

 Diameter of bearing surface

 Width of land and groove impressions

 When used in conjunction with stereo 

or comparison microscope

 Various levels of quality and readout

 Typically are periodically checked against 

a NIST certified gauge block
Current Technology Used in the Laboratory – William E. Demuth II

Measuring Devices - Dimensional

 Caliper
Current Technology Used in the Laboratory – William E. Demuth II

Measuring Devices - Dimensional

 Caliper

 Used for dimensional measurements 

on fired evidence
Current Technology Used in the Laboratory – William E. Demuth II

Measuring Devices - Dimensional

 Caliper

 Used for dimensional measurements 

on fired evidence

 Determining caliber for cartridge cases 

with inadequate/misleading headstamp

markings
Current Technology Used in the Laboratory – William E. Demuth II

Measuring Devices - Dimensional

 Caliper

 Used for dimensional measurements 

on fired evidence

 Determining caliber for cartridge cases 

with inadequate/misleading headstamp 

markings

 Caliber of fired bullets
Current Technology Used in the Laboratory – William E. Demuth II

Measuring Devices - Dimensional

 Caliper

 Used for dimensional measurements 

on fired evidence

 Determining caliber for cartridge cases 

with inadequate/misleading headstamp 

markings

 Caliber of fired bullets

 Diameter of bearing surface
Current Technology Used in the Laboratory – William E. Demuth II

Measuring Devices - Dimensional

 Caliper

 Used for dimensional measurements 

on fired evidence

 Determining caliber for cartridge cases 

with inadequate/misleading headstamp 

markings

 Caliber of fired bullets

 Diameter of bearing surface

 Width of land and groove impressions
Current Technology Used in the Laboratory – William E. Demuth II

Measuring Devices - Dimensional

 Caliper

 Used for dimensional measurements 

on fired evidence

 Determining caliber for cartridge cases 

with inadequate/misleading headstamp 

markings

 Caliber of fired bullets

 Diameter of bearing surface

 Width of land and groove impressions

 When used in conjunction with stereo 

or comparison microscope
Current Technology Used in the Laboratory – William E. Demuth II

Measuring Devices - Dimensional

 Caliper

 Used for dimensional measurements 

on fired evidence

 Determining caliber for cartridge cases 

with inadequate/misleading headstamp 

markings

 Caliber of fired bullets

 Diameter of bearing surface

 Width of land and groove impressions

 When used in conjunction with stereo 

or comparison microscope

 Various levels of quality and readout
Current Technology Used in the Laboratory – William E. Demuth II

Measuring Devices - Dimensional

 Caliper

 Used for dimensional measurements on 

fired evidence

 Determining caliber for cartridge cases with 

inadequate/misleading headstamp markings

 Caliber of fired bullets

 Diameter of bearing surface

 Width of land and groove impressions

 When used in conjunction with stereo 

or comparison microscope

 Various levels of quality and readout

 Typically are periodically checked against 

a NIST certified gauge block
Current Technology Used in the Laboratory – William E. Demuth II

Measuring Devices - Dimensional

 Reticules
Current Technology Used in the Laboratory – William E. Demuth II

Measuring Devices - Dimensional

 Reticules

 Employed as a component of a stereo 

or comparison microscope
Current Technology Used in the Laboratory – William E. Demuth II

Measuring Devices - Dimensional

 Reticules

 Employed as a component of a stereo 

or comparison microscope

 Used for small scale dimensional 

measurements on fired evidence
Current Technology Used in the Laboratory – William E. Demuth II

Measuring Devices - Dimensional

 Reticules

 Employed as a component of a stereo 

or comparison microscope

 Used for small scale dimensional 

measurements on fired evidence

 Caliber of fired bullets
Current Technology Used in the Laboratory – William E. Demuth II

Measuring Devices - Dimensional

 Reticules

 Employed as a component of a stereo 

or comparison microscope

 Used for small scale dimensional 

measurements on fired evidence

 Caliber of fired bullets

 Diameter of bearing surface
Current Technology Used in the Laboratory – William E. Demuth II

Measuring Devices - Dimensional

 Reticules

 Employed as a component of a stereo 

or comparison microscope

 Used for small scale dimensional 

measurements on fired evidence

 Caliber of fired bullets

 Diameter of bearing surface

 Width of land and groove impressions
Current Technology Used in the Laboratory – William E. Demuth II

Measuring Devices - Dimensional

 Reticules

 Employed as a component of a stereo 

or comparison microscope

 Used for small scale dimensional 

measurements on fired evidence

 Caliber of fired bullets

 Diameter of bearing surface

 Width of land and groove impressions

 Ocular with etched division lines
Current Technology Used in the Laboratory – William E. Demuth II

Measuring Devices - Dimensional

 Reticules

 Employed as a component of a stereo 

or comparison microscope

 Used for small scale dimensional 

measurements on fired evidence

 Caliber of fired bullets

 Diameter of bearing surface

 Width of land and groove impressions

 Ocular with etched division lines

 Filar micrometer
Current Technology Used in the Laboratory – William E. Demuth II

Measuring Devices - Dimensional

 Reticules

 Employed as a component of a stereo 

or comparison microscope

 Used for small scale dimensional 

measurements on fired evidence

 Caliber of fired bullets

 Diameter of bearing surface

 Width of land and groove impressions

 Ocular with etched division lines

 Filar micrometer

 Digital camera software
Current Technology Used in the Laboratory – William E. Demuth II

Measuring Devices - Dimensional

 Reticules

 Employed as a component of a stereo or 

comparison microscope

 Used for small scale dimensional 

measurements on fired evidence

 Caliber of fired bullets

 Diameter of bearing surface

 Width of land and groove impressions

 Ocular with etched division lines

 Filar micrometer

 Digital camera software

 All of these methods should be 

performance checked regularly against a 

certified stage micrometer
Current Technology Used in the Laboratory – William E. Demuth II

Measuring Devices - Dimensional

 MP6 Measuring Projector
Current Technology Used in the Laboratory – William E. Demuth II

Measuring Devices - Dimensional

 MP6 Measuring Projector

 Used for dimensional 

measurements on fired 

evidence
Current Technology Used in the Laboratory – William E. Demuth II

Measuring Devices - Dimensional

 MP6 Measuring Projector

 Used for dimensional 

measurements on fired 

evidence

 Caliber of fired bullets
Current Technology Used in the Laboratory – William E. Demuth II

Measuring Devices - Dimensional

 MP6 Measuring Projector

 Used for dimensional 

measurements on fired 

evidence

 Caliber of fired bullets

 Diameter of bearing surface
Current Technology Used in the Laboratory – William E. Demuth II

Measuring Devices - Dimensional

 MP6 Measuring Projector

 Used for dimensional 

measurements on fired 

evidence

 Caliber of fired bullets

 Diameter of bearing surface

 Width of land and groove 

impressions
Current Technology Used in the Laboratory – William E. Demuth II

 MP6 Measuring Projector

Measuring Devices - Dimensional
Current Technology Used in the Laboratory – William E. Demuth II

 MP6 Measuring Projector

 Image of item is projected on 

a screen with a fixed anchor 

line

Measuring Devices - Dimensional
Current Technology Used in the Laboratory – William E. Demuth II

 MP6 Measuring Projector

 Image of item is projected on 

a screen with a fixed anchor 

line

 The stage is connected 

directly or indirectly to a 

measuring device

Measuring Devices - Dimensional
Current Technology Used in the Laboratory – William E. Demuth II

Fired Evidence

 Cartridge Cases

 Inadequate headstamp
Current Technology Used in the Laboratory – William E. Demuth II

Fired Evidence

 Cartridge Cases

 Inadequate headstamp

 Misleading headstamp
Current Technology Used in the Laboratory – William E. Demuth II

Fired Evidence

 Cartridge Cases
Current Technology Used in the Laboratory – William E. Demuth II

Fired Evidence

 Cartridge Cases

 Dimensional measurements taken
Current Technology Used in the Laboratory – William E. Demuth II

Fired Evidence

 Cartridge Cases

 Dimensional measurements taken

 Micrometer
Current Technology Used in the Laboratory – William E. Demuth II

Fired Evidence

 Cartridge Cases

 Dimensional measurements taken

 Micrometer

 Caliper
Current Technology Used in the Laboratory – William E. Demuth II

Fired Evidence

 Cartridge Cases

 Dimensional measurements taken

 Micrometer

 Caliper

 Dimensions compared to published standards
Current Technology Used in the Laboratory – William E. Demuth II

Fired Evidence

 Cartridge Cases

 Dimensional measurements taken

 Micrometer

 Caliper

 Dimensions compared to published standards

 Reloading manuals
Current Technology Used in the Laboratory – William E. Demuth II

Fired Evidence

 Cartridge Cases

 Dimensional measurements taken

 Micrometer

 Caliper

 Dimensions compared to published standards

 Reloading manuals

 Reference works (Cartridges of the World)
Current Technology Used in the Laboratory – William E. Demuth II

Fired Evidence

 Cartridge Cases

 Dimensional measurements taken

 Micrometer

 Caliper

 Dimensions compared to published standards

 Reloading manuals

 Reference works (Cartridges of the World)

 Commercially available databases
Current Technology Used in the Laboratory – William E. Demuth II

Fired Evidence

 Cartridge Cases
Current Technology Used in the Laboratory – William E. Demuth II

Fired Evidence

 Cartridge Cases

 Potential pitfalls
Current Technology Used in the Laboratory – William E. Demuth II

Fired Evidence

 Cartridge Cases

 Potential pitfalls

 Dimensional tolerances vary slightly by manufacturer
Current Technology Used in the Laboratory – William E. Demuth II

Fired Evidence

 Cartridge Cases

 Potential pitfalls

 Dimensional tolerances vary slightly by manufacturer

 Due to obturation, dimensions of fired cartridge cases may 

vary slightly from unfired cartridges
Current Technology Used in the Laboratory – William E. Demuth II

Fired Evidence

 Cartridge Cases

 Potential pitfalls

 Dimensional tolerances vary slightly by manufacturer

 Due to obturation, dimensions of fired cartridge cases may 

vary slightly from unfired cartridges

 The “human factor”
Current Technology Used in the Laboratory – William E. Demuth II

Fired Evidence

 Cartridge Cases

 Potential pitfalls

 Dimensional tolerances vary slightly by manufacturer

 Due to obturation, dimensions of fired cartridge cases may 

vary slightly from unfired cartridges

 The “human factor”

 Reading the device
Current Technology Used in the Laboratory – William E. Demuth II

Fired Evidence

 Cartridge Cases

 Potential pitfalls

 Dimensional tolerances vary slightly by manufacturer

 Due to obturation, dimensions of fired cartridge cases may 

vary slightly from unfired cartridges

 The “human factor”

 Reading the device

 Selecting the proper areas to measure
Current Technology Used in the Laboratory – William E. Demuth II

Fired Evidence

 Cartridge Cases

 Potential pitfalls

 Dimensional tolerances vary slightly by manufacturer

 Due to obturation, dimensions of fired cartridge cases may 

vary slightly from unfired cartridges

 The “human factor”

 Reading the device

 Selecting the proper areas to measure

 Generally poor technique
Current Technology Used in the Laboratory – William E. Demuth II

Fired Evidence

 Bullets

 Three class characteristics are mathematically linked to 

each other
Current Technology Used in the Laboratory – William E. Demuth II

Fired Evidence

 Bullets

 Three class characteristics are mathematically linked to 

each other

 Caliber – diameter of the bullet (D)
Current Technology Used in the Laboratory – William E. Demuth II

Fired Evidence

 Bullets

 Three class characteristics are mathematically linked to 

each other

 Caliber – diameter of the bullet (D)

 Number of land and groove impressions (N)

5
Current Technology Used in the Laboratory – William E. Demuth II

Fired Evidence

 Bullets

 Three class characteristics are mathematically linked to 

each other

 Caliber – diameter of the bullet (D)

 Number of land and groove impressions (N)

 Width of the land and groove impressions (L, G)
Current Technology Used in the Laboratory – William E. Demuth II

Fired Evidence

 Bullets

 Three class characteristics are mathematically linked to 

each other

 Caliber – diameter of the bullet (D)

 Number of land and groove impressions (N)

 Width of the land and groove impressions (L, G)

 If two are known, the third can be derived

 D = (L + G) (N) / P
Current Technology Used in the Laboratory – William E. Demuth II

Fired Evidence

 Bullets

 Example:

 Damage to bearing surface preventing diameter measurement 

(D)

 Measured land impression widths = .056” (L)

 Measured groove impression widths = .122” (G)

 Number of land and groove impressions = 6 (N)
Current Technology Used in the Laboratory – William E. Demuth II

Fired Evidence

 Bullets

 Example:

 Damage to bearing surface preventing diameter measurement 

(D)

 Measured land impression widths = .056” (L)

 Measured groove impression widths = .122” (G)

 Number of land and groove impressions = 6 (N)

 D = (L + G) (N) / P
Current Technology Used in the Laboratory – William E. Demuth II

Fired Evidence

 Bullets

 Example:

 Damage to bearing surface preventing diameter measurement 

(D)

 Measured land impression widths = .056” (L)

 Measured groove impression widths = .122” (G)

 Number of land and groove impressions = 6 (N)

 D = (L + G) (N) / P

 D = (.061” + .122”) (6) / 3.14159265
Current Technology Used in the Laboratory – William E. Demuth II

Fired Evidence

 Bullets

 Example:

 Damage to bearing surface preventing diameter measurement 

(D)

 Measured land impression widths = .056” (L)

 Measured groove impression widths = .122” (G)

 Number of land and groove impressions = 6 (N)

 D = (L + G) (N) / P

 D = (.061” + .122”) (6) / 3.14159265

 D = .349”
Current Technology Used in the Laboratory – William E. Demuth II

Fired Evidence

 Bullets

 Diameter can be measured

 Macroscopically using

 Caliper

 Micrometer
Current Technology Used in the Laboratory – William E. Demuth II

Fired Evidence

 Bullets

 Diameter can be measured

 Macroscopically using

 Caliper

 Micrometer

 Under magnification using

 Reticules 

 MP6 measuring projector
Current Technology Used in the Laboratory – William E. Demuth II

Fired Evidence

 Bullets

 Land and groove impression widths can be measured

 Under magnification using
Current Technology Used in the Laboratory – William E. Demuth II

Fired Evidence

 Bullets

 Land and groove impression widths can be measured

 Under magnification using

 Reticules
Current Technology Used in the Laboratory – William E. Demuth II

Fired Evidence

 Bullets

 Land and groove impression widths can be measured

 Under magnification using

 Reticules 

 MP6 measuring projector
Current Technology Used in the Laboratory – William E. Demuth II

Fired Evidence

 Bullets

 Land and groove impression widths can be measured

 Under magnification using

 Reticules 

 MP6 measuring projector

 Ruler
Current Technology Used in the Laboratory – William E. Demuth II

Fired Evidence

 Bullets

 Land and groove impression widths can be measured

 Under magnification using

 Reticules 

 MP6 measuring projector

 Ruler

 Caliper (air gap)
Current Technology Used in the Laboratory – William E. Demuth II

Fired Evidence

 Bullets

 Land and groove impression widths can be measured

 Under magnification using

 Reticules 

 MP6 measuring projector

 Ruler

 Caliper (air gap)

 Micrometer (air gap)
Current Technology Used in the Laboratory – William E. Demuth II

Fired Evidence

 Bullets
Current Technology Used in the Laboratory – William E. Demuth II

Fired Evidence

 Bullets

 Potential pitfalls
Current Technology Used in the Laboratory – William E. Demuth II

Fired Evidence

 Bullets

 Potential pitfalls

 Damage to bullet can cause distortion of dimensions
Current Technology Used in the Laboratory – William E. Demuth II

Fired Evidence

 Bullets

 Potential pitfalls

 Damage to bullet can cause distortion of dimensions

 Poor shoulder definition
Current Technology Used in the Laboratory – William E. Demuth II
Current Technology Used in the Laboratory – William E. Demuth II

Fired Evidence

 Bullets

 Potential pitfalls

 Damage to bullet can cause distortion of dimensions

 Poor shoulder definition

 The “human factor”
Current Technology Used in the Laboratory – William E. Demuth II

Fired Evidence

 Bullets

 Potential pitfalls

 Damage to bullet can cause distortion of dimensions

 Poor shoulder definition

 The “human factor”

 Reading the device
Current Technology Used in the Laboratory – William E. Demuth II

Fired Evidence

 Bullets

 Potential pitfalls

 Damage to bullet can cause distortion of dimensions

 Poor shoulder definition

 The “human factor”

 Reading the device

 Interpolation between division marks on 

 reticules and rulers
Current Technology Used in the Laboratory – William E. Demuth II

Fired Evidence

 Bullets

 Potential pitfalls

 Damage to bullet can cause distortion of dimensions

 Poor shoulder definition

 The “human factor”

 Reading the device

 Interpolation between division marks on 

 reticules and rulers

 Selecting the correct anchor points on the shoulders
Current Technology Used in the Laboratory – William E. Demuth II

Fired Evidence

 Bullets
Current Technology Used in the Laboratory – William E. Demuth II

Fired Evidence

 Bullets

 Potential pitfalls

 Damage to bullet can cause distortion of dimensions

 Poor shoulder definition

 The “human factor”

 Reading the device

 Interpolation between division marks on reticules and 

rulers

 Selecting the correct anchor points on the shoulders

 Generally poor technique
Current Technology Used in the Laboratory – William E. Demuth II

Conclusion

 Over the course of this discussion, an introduction to the 

basic instrumentation found within the modern Firearms 

Unit was presented.
Current Technology Used in the Laboratory – William E. Demuth II

Conclusion

 Over the course of this discussion, an introduction to the 

basic instrumentation found within the modern Firearms 

Unit was presented.

 This included a brief description of:
Current Technology Used in the Laboratory – William E. Demuth II

Conclusion

 Over the course of this discussion, an introduction to the 

basic instrumentation found within the modern Firearms 

Unit was presented.

 This included a brief description of:

 Microscopes
Current Technology Used in the Laboratory – William E. Demuth II

Conclusion

 Over the course of this discussion, an introduction to the 

basic instrumentation found within the modern Firearms 

Unit was presented.

 This included a brief description of:

 Microscopes

 Measuring Devices
Current Technology Used in the Laboratory – William E. Demuth II

Conclusion

 Over the course of this discussion, an introduction to the 

basic instrumentation found within the modern Firearms 

Unit was presented.

 This included a brief description of:

 Microscopes

 Measuring Devices

 Mass/weight, force
Current Technology Used in the Laboratory – William E. Demuth II

Conclusion

 Over the course of this discussion, an introduction to the 

basic instrumentation found within the modern Firearms 

Unit was presented.

 This included a brief description of:

 Microscopes

 Measuring Devices

 Mass/weight, force

 Dimensional
Current Technology Used in the Laboratory – William E. Demuth II

Conclusion

 Over the course of this discussion, an introduction to the 

basic instrumentation found within the modern Firearms 

Unit was presented.

 This included a brief description of:

 Microscopes

 Measuring Devices

 Mass/weight, force

 Dimensional

 The types of measurements collected
Current Technology Used in the Laboratory – William E. Demuth II

Conclusion

 Over the course of this discussion, an introduction to the 

basic instrumentation found within the modern Firearms 

Unit was presented.

 This included a brief description of:

 Microscopes

 Measuring Devices

 Mass/weight, force

 Dimensional

 The types of measurements collected

 Purpose
Current Technology Used in the Laboratory – William E. Demuth II

Conclusion

 Over the course of this discussion, an introduction to the 

basic instrumentation found within the modern Firearms 

Unit was presented.

 This included a brief description of:

 Microscopes

 Measuring Devices

 Mass/weight, force

 Dimensional

 The types of measurements collected

 Purpose

 Possible issues